lesson plan on energy unit merged
TRANSCRIPT
Lesson Plan on Energy Unit
Holl ie O’Brien
MIT Fal l 2013
11.129 Final Portfol io Project
Energy Unit Day 1
Concepts 1. Energy is the ability to do work and is used in order to perform work.
2. Power is the rate at which work is done.
3. There are mathematical representations of work and power.
4. There are various units of energy, work, and power.
Key Questions 1. How do you describe the relationship between energy, work, and power?
2. How do you represent the relationships between the three, using mathematical formulas?
Learning Objectives: Students will able to define and contrast energy, work, and power.
Given mass, distance, and time, the student will be able to calculate work and power using appropriate
units.
Alignment of learning objectives with Massachusetts State Framework:
Conservation of Energy and Momentum
Broad Concept: The laws of conservation of energy and momentum provide alternate approaches to predict and describe the movement of objects.
2.1 Interpret and provide examples that illustrate the law of conservation of energy. *
2.2 Provide examples of how energy can be transformed from kinetic to potential and vice versa.
2.3 Apply quantitatively the law of conservation of mechanical energy to simple systems.
2.4 Describe the relationship among energy, work, and power both
conceptually and quantitatively.
2.6 Identify appropriate standard international units of
measurement for energy, work, power, and momentum.
Detailed Lesson Plans:
Do Now:
Introduce energy with word association brainstorm –What do students think about when they hear the term “Energy?”
Where/how do you use energy in your lives? Name a few things that we do that use
energy.
What happens when we don’t have access to energy (electric power)(e.g. summer
blackout/ice storms)?
Lead to concepts of energy in a useful form to provide heat, power or do work for human use.
Note – everything is either capable of providing energy or has energy, until there is none left – has been transformed to something else
Hand out vocabulary sheet –indicate that students should fill in as go. Have copy on the board –fill in definitions and equations in appropriate places as proceed.
Watch Eureka! Video at
http://www.youtube.com/watch?v=xBnS23U_ao4&list=PLT8RCCgU0GtmKuCDkx2MMk2x7UwJrPoD5
Write Definitions on the board (or you could just give them the sheet already filled in)
A force is a push, pull, or twist
Force = mass X acceleration Drop a ball . What is pulling it towards the ground? Gravity. (Acceleration of gravity (9.81 m/s 2). ) Energy is the ability to do work
Work is a force acting over a distance to move an object
Work = force X distance
Power is how fast work is done (or the rate at which work is done)
Power=work/time OR Power=energy used/time
Re-enforce the concept of work with the Student Push/Pull Demo
Ask for two volunteers.
Have one push against the wall and one push on a chair so that the chair moves at least 0.5 meters.
Discuss as a class o Did either one or both of these students do any work? The one pushing on the chair did
work; the other did not. “Work” requires that an object be moved. o Did either of these expend energy? Yes – energy contributes to doing work, but not all
energy successfully does work Go over SI Units (System Internationale)
We use this so that parts made in the US and in other parts of the world match (an engine built in
Japan can fit in a car made in the US since the measurements are the same)
Mass kilogram (kg)
Distance meters (m)
Time second (s)
Velocity meters per second (m/s)
Acceleration meters per second squared (m/s2)
Energy Joule (J)
Force Newton (N)
o A Newton is also a kg*m/s2 o We determine this by plugging the units into the equation o Force=mass*acceleration
Work Joule (J) ƒ o A Joule is also a N*m (work = force x distance)
Power Watt (W) o A Watt is also a J/s or N*m/s
o An easy way to remember the Watt is to ask the k ids “Watt (What) is the unit of Power?” They like that.
There are two units that we will use to measure energy 1. British Thermal Unit (BTU): There are 1055 Joules in one BTU. This unit is used when we
measure large amounts of energy. For example we would measure the amount of energy is the
USA’s oil reserves in BTU. 2. Kilowatt Hour (kWh): This is how the electrical energy you use in your home is measured on your
electricity bill. It is how many kilowatts you use in an hour.
a. 1000 W = kW b. energy = power (kW)* time (h)
Extension – besides electrical energy, what other type of energy does our home consume a lot of in the north? HEAT! does anyone know the energy term used to measure the amount of natural gas we use to heat our homes?
Therm. 1 therm = 100,000 BTU.
Closure: Assign homework
Ask – what did we learn today? Can anyone define work, power, energy?
Homework:
Read Chapter 8 pages 103-105 in textbook
Complete the Work and Power sections in the Student Packet
Labs/Demos/Web Resources: See all the resources
Assessment Components: Students will be working on the packet to assess learning
Energy Unit Day 2
Concepts 5. Energy is the ability to do work and is used in order to perform work.
6. Power is the rate at which work is done.
7. There are mathematical representations of work and power.
8. There are various units of energy, work, and power.
Key Questions 3. How do you describe the relationship between energy, work, and power?
4. How do you represent the relationships between the three, using mathematical formulas?
Learning Objectives: Given mass, distance, and time, the student will be able to calculate work and power using
appropriate units.
Given the conversion formulas, the student will be able to calculate horsepower and kilowatt equivalence.
Students will use measurement tools to apply the concepts of work, power, and energy to a real life example
Alignment of learning objectives with State Framework:
Mass Conservation of Energy and Momentum
Broad Concept: The laws of conservation of energy and momentum provide alternate approaches to predict and describe the movement of objects.
2.1 Interpret and provide examples that illustrate the law of conservation of energy. *
2.2 Provide examples of how energy can be transformed from kinetic to potential and vice versa.
2.3 Apply quantitatively the law of conservation of mechanical energy to simple systems.
2.4 Describe the relationship among energy, work, and power both conceptually and quantitatively.
2.6 Identify appropriate standard international units of measurement for energy, work,
power, and momentum.
Detailed Lesson Plans: Have student demonstrate human power experiment – (no measurement)
Discuss what happened – use discussion to review energy, work, and power– go over equations and units for force, work, power.
o Work = force x distance Where Force = mass x acceleration
o Power = work/time
Ask students – if we wanted to determine how much work student just did, what could we measure? (mass, time, distance – can’t measure force directly in this case)
Introduce Human Power Activity. This activity will require students to collect data for mass, distance and time. The activity sheet lists equipment needed, but you may want to substitute heavier bottles so the students can “feel” the work they do (2-liter or gallon milk jugs work well).
Using the data collected in the Activity, calculate average time and apply the appropriate formulas to calculate work and power. Calculate a few of the trials in class, have students finish the calculations for homework.
Hold up a 60 Watt light bulb and ask if anybody in the class produced enough power to light the
bulb (hopefully no one actually does). Ask if they could produce more power possibly with their legs. (Give the example of the human powered bike headlights).
Ask and/or lead a student (on the board) through a calculation of how many of themselves it
would take to light the bulb, based on their power output from the activity. # of people to light
60 Watt bulb = 60 watts/power from the activity. (For example, if the student’s name was Nate and it took 300 of them to light the bulb, it is therefore a 300 natepower bulb.)
If time allows, convert watts to horsepower in activity
Homework:
Read page 104-111
Finish Power part of packet
Labs/Demos/Web Resources: See Resources
Assessment Components: Students will complete the homework.
Energy Unit Day 3
Concepts 9. Energy is the ability to do work and is used in order to perform work.
10. Power is the rate at which work is done.
11. There are mathematical representations of work and power.
12. There are various units of energy, work, and power.
Key Questions 5. How do you describe the relationship between energy, work, and power?
6. How do you represent the relationships between the three, using mathematical formulas?
Learning Objectives: Given mass, distance, and time, the student will be able to calculate work and power using appropriate units.
Given the conversion formulas, the student will be able to calculate horsepower and kilowatt
equivalence.
Students will use measurement tools to apply the concepts of work, power, and energy to a real life example
Alignment of learning objectives with with State Framework:
Conservation of Energy and Momentum
Broad Concept: The laws of conservation of energy and momentum provide alternate approaches to predict and describe the movement of objects.
2.1 Interpret and provide examples that illustrate the law of conservation of energy. *
2.2 Provide examples of how energy can be transformed from kinetic to potential and vice versa.
2.3 Apply quantitatively the law of conservation of mechanical energy to simple systems.
2.4 Describe the relationship among energy, work, and power both conceptually and quantitatively.
2.6 Identify appropriate standard international units of measurement for energy, work, power, and momentum.
Detailed Lesson Plans: You will probably need to use the beginning of this class to wrap up the Human Power Activity.
Start the rollercoaster lab online. It will take the whole period.
Homework:
Finish the packet
Labs/Demos/Web Resources: See resources.
Assessment Components: Students will be assessed using the packet.
Energy Unit Day 4
Concepts 13. Energy is the ability to do work and is used in order to perform work.
14. Power is the rate at which work is done.
15. There are mathematical representations of work and power.
16. There are various units of energy, work, and power.
Key Questions 7. How do you describe the relationship between energy, work, and power?
8. How do you represent the relationships between the three, using mathematical formulas?
Learning Objectives: Students will interpret examples that illustrate the law of conservation of energy.
Students will identify how energy can be transformed from kinetic to potential and vice versa.
Alignment of learning objectives with with State Framework:
Conservation of Energy and Momentum
Broad Concept: The laws of conservation of energy and momentum provide alternate approaches to predict and describe the movement of objects.
2.1 Interpret and provide examples that illustrate the law of conservation of energy. *
2.2 Provide examples of how energy can be transformed from kinetic to potential and vice versa.
2.3 Apply quantitatively the law of conservation of mechanical energy to simple systems.
2.4 Describe the relationship among energy, work, and power both conceptually and quantitatively.
2.6 Identify appropriate standard international units of measurement for energy, work,
power, and momentum.
Detailed Lesson Plans: Finish the online rollercoaster lab.
Go over the whole homework packet and check in class.
The students can ask questions since the quiz is on day 5.
Homework:
Study for Quiz
Labs/Demos/Web Resources: See resources
Assessment Components: Students will be quizzed.
Energy Unit Day 5
Concepts 17. Energy is the ability to do work and is used in order to perform work.
18. Power is the rate at which work is done.
19. There are mathematical representations of work and power.
20. There are various units of energy, work, and power.
Key Questions 9. How do you describe the relationship between energy, work, and power?
10. How do you represent the relationships between the three, using mathematical formulas?
Learning Objectives: Students will describe the relationship among energy, work, and power both conceptually and
quantitatively.
Alignment of learning objectives with with State Framework:
Conservation of Energy and Momentum
Broad Concept: The laws of conservation of energy and momentum provide alternate approaches to predict and describe the movement of objects.
2.1 Interpret and provide examples that illustrate the law of conservation of energy. *
2.2 Provide examples of how energy can be transformed from kinetic to potential and vice versa.
2.3 Apply quantitatively the law of conservation of mechanical energy to simple systems.
2.4 Describe the relationship among energy, work, and power both conceptually and quantitatively.
2.6 Identify appropriate standard international units of measurement for energy, work, power, and momentum.
Detailed Lesson Plans: Answer any last minute questions to prep for the quiz.
Allow at least half the period for the students to complete the Energy Basics Assessment
Have students read pg. 111-118 to prepare to cover mechanical machines.
Labs/Demos/Web Resources: See resources.
Assessment Components: Students are quizzed.
Definition and Formulae
Key Terms
Force A force is a push, pull, or twist
=mass x acceleration Newton (N) =kg/m/s2
Joule the SI unit for energy and work.
J = W·s = N·m
Energy
the ability to do work
=power x time
Joule
Work
Work is a force acting over a distance to move an object
= force x distance
Joule (J)
Power The rate at which work is done
= work / time (or =energy/time)
Watt = J/s
Meter
the SI (Standard International) unit for distance
m
Kilogram
the SI unit for mass
kg
Btu
The amount of energy needed to raise 1 lb of water 1 degree Fahrenheit (1 Btu ~ heat energy from one wooden match)
1 Btu = 1055 Joules
Kilowatt
Typical unit for electrical power
1 kW = 1000 watts
Horse power
Unit for mechanical or electrical power
1 hp = 746 watts
Kilowatt hour
Typical unit for electrical energy
kWh
Definition and Formulae
Force:
Energy:
Work:
Power:
Meter:
Kilogram:
Newton:
Joule:
Btu:
Watt:
Kilowatt:
Energy Basics Assessment
Name: ________________________
You have 20 minutes to complete all of the questions. Questions 1-4 all correspond to the diagram below.
Questions 5-9 are separate and must be answered within the allotted time.
1. Write the equation for WORK.
2. If it takes 5 newtons of force to move the wagon 5 meters, how much work is being done? Remember to
use the correct units.
3. What are the units for POWER?
4. If it took 10 seconds to move the wagon, how much
power was provided?
5. What is the definition of ENERGY?
6. What S.I. unit do we use for MASS?
7. A BTU is used to describe what type of measurement?
8. FORCE is measured using (please circle the correct
answer) a. Newtons
b. Joules
c. Kilograms
9. List three choices you can make to reduce the amount of energy you use in your life.
10. Explain why it is important to think about how much energy you use in your life.
Energy Basics Assessment Name: ________________________ You have 20 minutes to complete all of the questions.
Questions 1-4 all correspond to the diagram below. Questions 5-9 are separate and must be answered within the
allotted time.
11. Write the equation for WORK.
Work = Force x distance
12. If it takes 5 newtons of force to move the wagon 5 meters, how much work is being done? Remember to
use the correct units.
Work = 5 newtons x 5 meters = 25 joules
13. What are the units for POWER?
Watts, Kilowatts
14. If it took 10 seconds to move the wagon, how much
power was provided?
Power = Work/time = 25 joules/10 seconds = 2.5 Watts
15. What is the definition of ENERGY?
The ability to do work
16. What S.I. unit do we use for MASS?
Kilograms
17. A BTU is used to describe what type of
measurement?
Another form of Energy Units –British Thermal Units
18. FORCE is measured using (please circle the correct
answer) a. Newtons
b. Joules c. Kilograms
19. List three choices you can make to reduce the
amount of energy you use in your life.
Turn of lights, buy energy efficient appliances, buy CFLs instead of incandescent, etc…
20. Explain why it is important to think about how much energy you use in your life.
The depletion of oil, environmental, societal, and economical
impacts.
Activity: Human Power
Purpose Work and power are important concepts that deal with energy. Work is a force over a
given distance and power is the amount of work done in an amount of time. The goal of this experiment is to get familiar with these concepts.
Equipment
1.Scale 2.Stopwatch 3.large bottle filled with water 4.meter stick 5.pole 6.rope
Procedure Set up the experiment:
1. Split into groups of 3-4 students.
2. Collect all equipment and materials necessary to conduct the activity.
3. Attach one end of the rope to the bottle and the other end to the middle of the
pole. 4. Measure the distance of the rope from the pole to the bottle and record it on the
space given (meters, m). Do work and collect data 5. Have each person stand on a chair and hold the pole horizontally so that the
bottle is suspended. Twist the pole so the rope winds around it, lifting the bottle.
Time how fast each person can wind the rope to bring the bottle all the way up to the pole. Record your data (in seconds).
6. Repeat so that each student has 3 tries, and record each time. 7. Using the given mass for your bottle, calculate Force by using:
a. Force (N) = mass (kg) x acceleration (m/ s2 )
b. Mass, m = given (kg) c. Acceleration due to gravity, a = 9.81 m/ s2
8. Record the force on the worksheet. 9. Use the worksheet to calculate average time for each person, work, power in
Watts and horsepower (remember that 1 hp = 746 watts).
Discussion Questions:
1. What is power?
2. What does it mean if one person has a higher value for power?
3. How many of you would it take to light a 60 Watt light bulb?
a. 60 Watts ÷ Your Power (from the table) = _________ “your name”power b. 60 Watts ÷ ________Watts = _________ “________ “ power
4. How does your person power compare to the horsepower in a car? (Use an estimated horsepower of 166)?
Name: _________________________ Date: ___________
Online Simulation Lab ROLLER COASTER PHYSICS
Purpose: The purpose of this simulation lab is to strengthen your understanding
of energy conservation in real-world applications. You will use a skateboarder and
his park to represent the roller coaster and its track. You will observe many other
physics concepts at work as well.
Pre-Lab Inquiry
What Do You Think?
You are asked to design a new roller coaster. It is totally up to you to determine
what the riders will experience. The only rule is that the coaster obeys the laws of
physics. Take a minute and brainstorm about a design you would like.
1. Name three adjectives that will describe your roller coaster.
2. Describe three features your roller coaster will have that will attract riders.
3. Name three variables that will affect the type of experience a rider will have. EXPLAIN.
4. Name three concepts of physics that the roller coaster must obey in order to be successful. EXPLAIN.
5. Draw a side-view sketch of your roller coaster design below.
Concept Review
Write out an explanation for each question below.
6. Define potential and kinetic energy.
7. Describe when potential and kinetic energy are at their highest on a roller
coaster.
8. How does conservation of energy apply to roller coasters?
9. How does friction affect a roller coaster?
10.What is responsible for the apparent change in weight that riders experience on coasters?
Internet Lab Activity
Open up the University of Colorado, PhET Energy Skate Park simulation:
1. Go to http://phet.colorado.edu/ 2. Click “Play with Sims…>” 3. Click the “Energy Skate Park” icon 4. Click “Run Now!” 5. Spend ONE MINUTE to explore the simulation and familiarize yourself with
the controls. 6. Click the “Reset” button in the top-right corner. Begin the exploration
below.
Exploration Questions
Use the simulation to answer the questions below.
1. Does the skater hit the same height on the opposite sides of the track? (Checkmark the “Show Grid” button to help you determine this!)
a. What must be true about the system for this to be possible?
b. Click the “Track Friction >>” button to adjust the friction settings. What do you observe about the skater as you adjust the setting?
2. Now, turn on the energy Pie Chart and Bar Graph. (You may need to move things around a little to see everything.)
a. On the visual aids, what color represents potential energy and which is kinetic energy?
b. When does the skater have the highest amount of kinetic energy? Potential energy?
c. When does the skater have the lowest amount of kinetic energy? Potential energy?
d. Describe how the bar graph changes as the skater moves along the track.
e. Explain which visual aid (pie chart or bar graph) helps you understand conservation of energy better, and why.
f. Keep your preferred visual aid open for the remainder of the investigation.
Build Your Roller Coaster
Use the simulation to build and test your roller coaster design from the Pre-Lab
Inquiry.
1. If you made any changes during the Exploration Questions, click “Reset” again.
2. Right-click the track and select “Roller Coaster Mode”. This keeps the skater attached.
3. Notice that you can zoom out to give yourself a wider view. You may want to do this as you build your coaster.
4. Drag in new pieces of track and manipulate the curves until you closely match your pre-lab sketch.
5. Drag and drop the rider to the location of the beginning and observe. DO NOT MAKE CHANGES YET.
a. The ride probably was not successful on the first attempt. If not, what physics concept(s) was violated?
b. Identify several adjustments you need to make.
6. After making the initial adjustments, try the ride again. Continue making adjustments until the ride becomes successful (rider makes it from one end to the other completely – does not have to make it back through).
7. Raise your hand and show the teacher your successful design. 8. Draw a side-view sketch of your successful design below.
9. Label the points of acceleration on your sketch. a. Down arrow = slowing down b. Up arrow = speeding up c. Circle arrow = changing direction
10.Click the “Track Friction >>” button and adjust the setting. 11.Run the rider through your track again and observe the changes.
a. Did the rider make it to the end?
b. What do you notice differently about the pie chart and/or bar graph?
12.Describe the changes you need to make to your design, as a result of the presence of friction.
13.Make the necessary adjustments until you achieve a successful ride with friction.
14.Raise your hand and show the teacher your friction-savvy coaster. 15.Draw a side-view sketch of your friction-savvy coaster below.
Post-Lab Questions:
1. List and explain the differences between each of your sketches.
2. At the top of a hill on the ride, most of the energy is _______________ and at the bottom of the hill, most of the energy is converted into _________________.
3. What are the equations for potential and kinetic energy?
4. If you were an engineer of an actual roller coaster, what information would you need to know in order to ensure that your coaster would be safe?
5. Would it be possible to predict the speeds that a coaster will reach before it’s ever placed on the track? How?
6. The most thrilling roller coasters usually contain vertical loops. What keeps the riders in their seats when they go upside-down?
7. Consider going around a horizontal turn to the right. If the coaster suddenly slipped off the track, what path would it follow? Draw a top-view sketch below.
8. You should have drawn the coaster following a straight line after it slipped off the track. Since that is the path it would take without the track, there must be an unbalanced force causing it to accelerate (turn) around the bend. What direction is that force pointing? Draw a top-view sketch of the force vectors below.
Name: _____KEY____________________ Date: ___________
Online Simulation Lab ROLLER COASTER PHYSICS
Purpose: The purpose of this simulation lab is to strengthen your understanding
of energy conservation in real-world applications. You will use a skateboarder and
his park to represent the roller coaster and its track. You will observe many other
physics concepts at work as well.
Pre-Lab Inquiry
What Do You Think?
You are asked to design a new roller coaster. It is totally up to you to determine
what the riders will experience. The only rule is that the coaster obeys the laws of
physics. Take a minute and brainstorm about a design you would like.
11.Name three adjectives that will describe your roller coaster.
ANSWERS WILL VARY WITH STUDENT
12.Describe three features your roller coaster will have that will attract riders.
ANSWERS WILL VARY WITH STUDENT
13.Name three variables that will affect the type of experience a rider will have. EXPLAIN.
ANSWERS WILL VARY WITH STUDENT
Possible answers include: height (affects max potential energy), speed/
velocity(force rider experiences), angle of incline of track, and ect. There
could be a variety of answers so make sure students explain.
14.Name three concepts of physics that the roller coaster must obey in order to be successful. EXPLAIN. Conservation of momentum, conservation of energy, Newton’s third law,
etc (as long as the student explains).
15.Draw a side-view sketch of your roller coaster design below.
ANSWERS WILL VARY WITH STUDENT
Concept Review
Write out an explanation for each question below.
16. Define potential and kinetic energy.
Potential—the energy that is possible due to position
Kinetic—the energy of motion
17. Describe when potential and kinetic energy are at their highest on a roller coaster.
Potential—top of the tallest hill
Kinetic—deals with motion. Max kinetic is when potential is lowest at the
bottom of a giant hill
18.How does conservation of energy apply to roller coasters?
As a rollercoaster goes down the hill, the potential energy turns into kinetic (no
energy is lost). As height decreases, speed increases.
19.How does friction affect a roller coaster?
Friction slows down a rollercoaster.
20.What is responsible for the apparent change in weight that riders experience on coasters?
The acceleration of a rider makes them feel lighter/heavier depending on if
they are counteracting gravity (going up a hill) or adding on to it (by dropping
down).
Internet Lab Activity
Open up the University of Colorado, PhET Energy Skate Park simulation:
7. Go to http://phet.colorado.edu/en/simulation/energy-skate-park-basics 8. Click “Run Now!” 9. Spend ONE MINUTE to explore the simulation and familiarize yourself with
the controls. 10.Click the “Reset” button in the top-right corner. Begin the exploration
below.
Exploration Questions
Use the simulation to answer the questions below.
3. Does the skater hit the same height on the opposite sides of the track? (Checkmark the “Show Grid” button to help you determine this!)
yes
a. What must be true about the system for this to be possible? It is frictionless
b. Click the “Track Friction >>” button to adjust the friction settings. What do you observe about the skater as you adjust the setting?
The more the friction, the sooner the rider comes to a stop.
4. Now, turn on the energy Pie Chart and Bar Graph. (You may need to move things around a little to see everything.)
a. On the visual aids, what color represents potential energy and which is kinetic energy?
Green—kinetic
Blue--potential
b. When does the skater have the highest amount of kinetic energy? Potential energy?
Max kinetic at bottom of parabola. Max potential at tops of parabola.
c. When does the skater have the lowest amount of kinetic energy? Potential energy?
Min kinetic at tops of parabola. Min potential at bottom of parabola.
d. Describe how the bar graph changes as the skater moves along the track.
The bars switch from kinetic to potential exactly.
e. Explain which visual aid (pie chart or bar graph) helps you understand conservation of energy better, and why.
ANSWERS WILL VARY WITH STUDENT
f. Keep your preferred visual aid open for the remainder of the investigation.
Build Your Roller Coaster
Use the simulation to build and test your roller coaster design from the Pre-Lab
Inquiry.
16.If you made any changes during the Exploration Questions, click “Reset” again.
17.Right-click the track and select “Roller Coaster Mode”. This keeps the skater attached.
18.Notice that you can zoom out to give yourself a wider view. You may want to do this as you build your coaster.
19.Drag in new pieces of track and manipulate the curves until you closely match your pre-lab sketch.
20.Drag and drop the rider to the location of the beginning and observe. DO NOT MAKE CHANGES YET.
a. The ride probably was not successful on the first attempt. If not, what physics concept(s) was violated?
ANSWERS WILL VARY WITH STUDENT
b. Identify several adjustments you need to make.
ANSWERS WILL VARY WITH STUDENT
21.After making the initial adjustments, try the ride again. Continue making adjustments until the ride becomes successful (rider makes it from one end to the other completely – does not have to make it back through).
22.Raise your hand and show the teacher your successful design. 23.Draw a side-view sketch of your successful design below.
ANSWERS WILL VARY WITH STUDENT
24.Label the points of acceleration on your sketch. a. Down arrow = slowing down b. Up arrow = speeding up c. Circle arrow = changing direction
25.Click the “Track Friction >>” button and adjust the setting. 26.Run the rider through your track again and observe the changes.
a. Did the rider make it to the end? (most likely no)
ANSWERS WILL VARY WITH STUDENT
b. What do you notice differently about the pie chart and/or bar graph? More and more energy went to thermal
27.Describe the changes you need to make to your design, as a result of the presence of friction.
ANSWERS WILL VARY WITH STUDENT (making the starting height higher or
lowering a loop-the-loop are two examples.)
28.Make the necessary adjustments until you achieve a successful ride with friction.
29.Raise your hand and show the teacher your friction-savvy coaster.
30.Draw a side-view sketch of your friction-savvy coaster below.
ANSWERS WILL VARY WITH STUDENT
Post-Lab Questions:
9. List and explain the differences between each of your sketches.
ANSWERS WILL VARY WITH STUDENT
10.At the top of a hill on the ride, most of the energy is ___potential_________ and at the bottom of the hill, most of the energy is converted into ____kinetic_____________.
11.What are the equations for potential and kinetic energy?
Kinetic energy: KE= 1
2 mv2
Potential Energy: PE=mgh
12.If you were an engineer of an actual roller coaster, what information would you need to know in order to ensure that your coaster would be safe?
ANSWERS WILL VARY WITH STUDENT
Examples include: speed, the force “g” that a rider will feel, strength of metal or
whatever materials it is built out of, and etc.
13.Would it be possible to predict the speeds that a coaster will reach before it’s ever placed on the track? How?
Yes, you can estimate by using the conservation of energy. As potential energy
switches to kinetic, you can solve for the velocity.
14.The most thrilling roller coasters usually contain vertical loops. What keeps the riders in their seats when they go upside-down?
Centripetal force—the component of the
momentum that is changing. **this is an important concept
15.Consider going around a horizontal turn to the right. If the coaster suddenly slipped off the track, what path would it follow? Draw a top-view sketch below.
straight line after it slipped off the track
16.You should have drawn the coaster following a straight line after it slipped off the track. Since that is the path it would take without the track, there must be an unbalanced force causing it to accelerate (turn) around the bend. What direction is that force pointing? Draw a top-view sketch of the force vectors below.
pointing perpendicular to the turn
D irections:
W o rk through this p acket of fi ll in the blank definitions, multiple choice questions,
a n d calculation p roblems. Show y our work whenever d oing a calculation. Show u nits
o n e very single s tep.
Work (CH 8 pg 103-104)
Definitions: (fill in the blank)
An impulse is a force acting over some amount of time to cause a change in
momentum. On the other hand, work is a ______________ acting over some
amount of ___________________ to cause a change in __________________.
Examples of work:
1. Indicate whether or not the following represent examples of work.
a. A teacher applies a force to a wall and becomes exhausted. Work done? Yes or No?
Explanation:_________________________________________
________________________________________________________________________________________________________________
________________________________________________________ b. A weightlifter lifts a barbell above her head.
Work done? Yes or No?
Explanation:_________________________________________________________________________________________________
________________________________________________________________________________________________________________
c. A waiter carries a tray full of meals across a dining room at a constant speed.
Work done? Yes or No?
Explanation:_________________________________________________________________________________________________________________________________________________________
_______________________________________________
d. A rolling marble hits a note card and moves it across a table.
Work done? Yes or No?
Explanation:_________________________________________________________________________________________________
________________________________________________________
________________________________________________________
e. A shot-putter launches the shot. Work done? Yes or No?
Explanation:_________________________________________
________________________________________________________________________________________________________________
________________________________________________________
2. Work is a ______________; a + or - sign on a work value indicates information about _______.
a. vector; the direction of the work vector b. scalar; the direction of the work vector
c. vector; whether the work adds or removes energy from the object d. scalar; whether the work adds or removes energy from the object
3. Which sets of units represent legitimate units for the quantity work? Circle all correct answers.
a. Joule b. N * m
c. Foot * pound d. kg * m/sec
e. kg * m/sec2 f. kg * m2/sec2
Helpful Hint!
The amount of work (W) done on an object by a given force can be calculated using the formula:
W = F*d*cosΘ Where F is the force and d is the distance over which the force acts and Θ is the
angle between F and d. It is important to recognize that the angle included in the equation is not just any old angle; it has a distinct definition that must be
remembered when solving such work problems.
Calculate!
4. For each situation below, calculate the amount of work done by the applied force.
5. Before beginning its initial descent, a roller coaster car is always pulled up the first hill to a high initial height. Work is done on the car (usually by a
chain) to achieve this initial height. A coaster designer is considering three different angles at which to drag the 2000-kg car train to the top of the 60-meter high hill. Her big question is: which angle would require the most
work?___________________ Show your answers and explain!!!
Angle Force Distance Work
35° 1.15 * 104 N 105 m
45° 1.41 * 104 N 84.9 m
55° 1.64 * 104 N 73.2 m
6. The following descriptions and their accompanying free-body diagrams
show the forces acting upon an object. For each case, calculate the work done by these forces; use the format of force • displacement • cosine(Θ). Finally, calculate the total work done by all forces.
7. When a force is applied to do work on an object, does the object always
accelerate? __________ a. Explain why or why not.
8. Determine the work done in the following situations.
a. Jim Neysweeper is applying a 21.6-N force downward at an angle of 57.2° with the horizontal to displace a broom a distance of 6.28 m.
b. Ben Pumpiniron applies an upward force to lift a 129-kg barbell to a height of 1.98 m at a constant speed.
c. An elevator lifts 12 occupants up 21 floors (76.8 meters) at a constant
speed. The average mass of the occupants is 62.8 kg.
Power (CH 8 pg 104-105)
Review:
1. A force acting upon an object to cause a displacement is known as _____.
a. Energy b. Potential
c. Kinetic d. Work
2. Two acceptable units for work are ________. Choose two. a. Joule b. Newton
c. Watt d. Newton•meter
Power as a Rate Quantity:
3. Power is defined as the _______ is done.
a. amount of work which b. direction at which work c. angle at which work
d. the rate at which work 4. Two machines (e.g., elevators) might do identical jobs (e.g., lift 10
passengers three floors) and yet the machines might have different power outputs. Explain how this can be so.
5. There are a variety of units for power. Which of the following would be fitting units of power (though perhaps not standard)? Include all that apply.
a. Watt b. Joule
c. Joule / second d. Hp
6. Two physics students, Will N. Andable and Ben Pumpiniron, are in the weightlifting room. Will lifts the 100-pound barbell over his head 10 times
in one minute; Ben lifts the 100-pound barbell over his head 10 times in 10 seconds. Which student does the most work? ______________
Which student delivers the most power? ______________ Explain your answers.
7. An often-used equation for power is Power = force*velocity Express an
understanding of the meaning of this equation by using it to explain what type of individuals would be the best choice for lineman on a football team.
Energy (CH 8 pg 105-111)
Definitions:
1. Potential energy is the ________________ energy of position possessed
by an object. 2. Kinetic energy is the energy of _________________.
3. The total amount of mechanical energy is merely the sum of the -
___________ energy and the _________________ energy. This sum is simply referred to as the total mechanical energy (abbreviated TME).
Calculate!
4. Read each of the following statements and identify them as having to do
with kinetic energy (KE), potential energy (PE) or both (B).
KE, PE or B? Statement:
a) If an object is at rest, it certainly does NOT possess this form of
energy. b) Depends upon object mass and
object height.
c) The energy an object possesses due to its motion.
d) The amount is expressed using the
unit joule (abbreviated J).
e) The energy stored in an object due
to its position (or height).
f) The amount depends upon the arbitrarily assigned zero level.
g) Depends upon object mass and
object speed.
h) If an object is at rest on the ground
(zero height), it certainly does NOT possess this form of energy.
5. A toy car is moving along with 0.40 joules of kinetic energy. If its speed
is doubled, then its new kinetic energy will be _______. a. 0.10 J
b. 0.20 J c. 0.80 J
d. 1.60 J e. still 0.40 J
6. A young boy's glider is soaring through the air, possessing 0.80 joules of
potential energy. If its speed is doubled and its height is doubled, then the new potential energy will be _______.
a. 0.20 J b. 0.40 J
c. 1.60 J d. 3.20 J
e. still 0.80 7. Which would ALWAYS be true of an object possessing a kinetic energy
of 0 joules? a. It is on the ground.
b. It is at rest. c. It is moving on the ground
d. It is moving. e. It is accelerating.
f. It is at rest above ground level g. It is above the ground.
h. It is moving above ground level. 8. Which would ALWAYS be true of an object possessing a potential
energy of 0 joules? a. It is on the ground.
b. It is at rest. c. It is moving on the ground
d. It is moving. e. It is accelerating.
f. It is at rest above ground level g. It is above the ground.
h. It is moving above ground level. 9. Calculate the kinetic energy of a 5.2 kg object moving at 2.4 m/s.
10. Calculate the potential energy of a 5.2 kg object positioned 5.8 m above
the ground.
11. Calculate the speed of a 5.2 kg object that possesses 26.1 J of kinetic
energy.
D irections:
W o rk through this p acket of fi ll in the blank definitions, multiple choice questions,
a n d calculation p roblems. Show y our work whenever d oing a calculation. Show u nits
o n e very single s tep.
Work (CH 8 pg 103-104)
Definitions: (fill in the blank)
An impulse is a force acting over some amount of time to cause a change in
momentum. On the other hand, work is a __object____________ acting over some
amount of ________distance___________ to cause a change in
__force________________.
Examples of work:
9. Indicate whether or not the following represent examples of work.
a. A teacher applies a force to a wall and becomes exhausted. Work done? Yes or No?
Explanation:____ This is not an example of work. The wall is
not displaced. A force must cause a displacement in order for work to
be done. ________________________________________________________
______ b. A weightlifter lifts a barbell above her head.
Work done? Yes or No?
Explanation:_______change in height means gravity acted against the displacement thus there is an increase in potential energy_
________________________________________________________
____________________________________________________________________
c. A waiter carries a tray full of meals across a dining room at a constant speed.
Work done? Yes or No?
Explanation:____ This is not an example of work. There is a force (the waiter pushes up on the tray) and
there is a displacement (the tray is moved horizontally across the room). Yet the force does not cause the displacement. To
cause a displacement, there must be a component of force in the direction of the displacement.
d. A rolling marble hits a note card and moves it across a table. Work done? Yes or No?
Explanation:_______ This is an example of work. There is a force (the marble pushing the card) which causes the card to be
displaced across the table. _______________________ e. A shot-putter launches the shot.
Work done? Yes or No?
Explanation:___ This is an example of work. There is a force (the hand pushing the shot put) which causes the
shot put to be displaced upwards before the person lets go. Once they let go, they are not doing work
anymore.______________________________________ 10. Work is a ______________; a + or - sign on a work value
indicates information about _______.
a. vector; the direction of the work vector b. scalar; the direction of the work vector
c. vector; whether the work adds or removes energy from the object d. scalar; whether the work adds or removes energy from the object
11. Which sets of units represent legitimate units for the quantity work? Circle all correct answers.
a. Joule b. N * m
c. Foot * pound d. kg * m/sec
e. kg * m/sec2 f. kg * m2/sec2
Helpful Hint!
The amount of work (W) done on an object by a given force can be calculated
using the formula:
W = F*d*cosΘ Where F is the force and d is the distance over which the force acts and Θ is the angle between F and d. It is important to recognize that the angle included in the
equation is not just any old angle; it has a distinct definition that must be remembered when solving such work problems.
Calculate!
12. For each situation below, calculate the amount of work done by the applied
force.
Diagram A Answer:
W = (100 N) * (5 m)* cos(0 degrees) = 500 J
The force and the displacement are given in the problem statement. It is said (or shown or implied) that the force and the displacement are both rightward. Since F
and d are in the same direction,the angle is 0 degrees.
Diagram B Answer:
W = (100 N) * (5 m) * cos(30 degrees) = 433 J
The force and the displacement are given in theproblem statement. It is said that the displacement is rightward. It is shown that the force is 30 degrees above the horizontal. Thus, the angle between F and d is 30 degrees.
Diagram C Answer:
W = (147 N) * (5 m) * cos(0 degrees) = 735 J
The displacement is given in the problem statement. The applied force must be 147 N since the 15-kg mass (Fgrav=147 N) is lifted at constant speed. Since F and d are
in the same direction, the angle is 0 degrees.
13. Before beginning its initial descent, a roller coaster car is always pulled up the first hill to a high initial height. Work is done on the car (usually by a
chain) to achieve this initial height. A coaster designer is considering three different angles at which to drag the 2000-kg car train to the top of the 60-
meter high hill. Her big question is: which angle would require the most work?___________________ Show your answers and explain!!!
Angle Force Distance Work
35° 1.15 * 104 N 105 m 1.18 x106 Joules
45° 1.41 * 104 N 84.9 m 1.18 x106 Joules
55° 1.64 * 104 N 73.2 m 1.18 x106 Joules
Be careful!
The angle in the table is the incline angle. The angle theta in the equation is the angle between F and d. If the F is parallel to the incline and the d is parallel to the incline, then the angle theta in
the work equation is 0 degrees. For this reason, W=F*d*cosine 0 degrees.
In each case, the work is approximately 1.18 x106 Joules.
The angle does not affect the amount of work done on the roller coaster car.
14. The following descriptions and their accompanying free-body diagrams
show the forces acting upon an object. For each case, calculate the work done by these forces; use the format of force • displacement • cosine(Θ).
Finally, calculate the total work done by all forces.
a. Only Fapp does work. Fgrav and Fnorm do not do work since a vertical force cannot cause a horizontal displacement. Wapp= (10 N)
* (5 m) *cos (0 degrees) = +50 Joules b. Only Ffrict does work. Fgrav and Fnorm do not do work since a
vertical force cannot cause a horizontal displacement. Wfrict =(10 N) * (5 m) * cos (180 degrees) = -50 Joules
c. Fapp and Ffrict do work. Fgrav and Fnorm do not do work since a vertical force cannot cause a horizontal displacement. Wapp = (10 N)
* (5 m) * cos (0 deg) = +50 Joules Wfrict = (10 N) * (5 m) * cos (180 deg) = -50 Joules
d. Neither of these forces do work. Forces do not do work when they
makes a 90-degree angle with the displacement. No work is done. e. Both Fgrav and Ftens do work. Forces do work when there is some
component of force in the same or opposite direction of the displacement. Wtens = (20 N)* (5 m) * cos (0 degrees) = +100 Joules
Wgrav = (20 N) * (5 m) * cos (180 degrees) = -100 Joules f. Same reasoning as part d
15. When a force is applied to do work on an object, does the object always
accelerate? __no________
a. Explain why or why not. if the force applied is in the direction opposite that the object is traveling, the
object will decelerate.
If the force applied is exactly equal in magnitude to frictional forces (and in the same direction of travel as the object), the object will remain at a constant velocity.
16. Determine the work done in the following situations. a. Jim Neysweeper is applying a 21.6-N force downward at an angle of
57.2° with the horizontal to displace a broom a distance of 6.28 m.
Go over in class w=f*d*cos(theta)
W=21.6 N*6.28m*cos(57.2)= 107.9 N*m
b. Ben Pumpiniron applies an upward force to lift a 129-kg barbell to a
height of 1.98 m at a constant speed.
Go over in class w=f*d*cos(theta)
W=129kg*9.81 m/s2*1.98m*cos(0)= 2506 N*m
c. An elevator lifts 12 occupants up 21 floors (76.8 meters) at a constant speed. The average mass of the occupants is 62.8 kg.
Go over in class w=f*d*cos(theta)
W=12*62.8kg*9.81 m/s2*76.8m*cos(0)= 567768 N*m
Power (CH 8 pg 104-105)
Review:
8. A force acting upon an object to cause a displacement is known as _____.
a. Energy b. Potential
c. Kinetic d. Work
9. Two acceptable units for work are ________. Choose two. a. Joule b. Newton
c. Watt d. Newton•meter
Power as a Rate Quantity:
10. Power is defined as the _______ is done.
a. amount of work which b. direction at which work c. angle at which work
d. the rate at which work 11. Two machines (e.g., elevators) might do identical jobs (e.g., lift 10
passengers three floors) and yet the machines might have different power outputs. Explain how this can be so.
The times it takes the elevators to lift—one might be faster
12. There are a variety of units for power. Which of the following would be fitting units of power (though perhaps not standard)? Include all that apply.
a. Watt
b. Joule c. Joule / second
d. Hp 13. Two physics students, Will N. Andable and Ben Pumpiniron, are in the
weightlifting room. Will lifts the 100-pound barbell over his head 10 times in one minute; Ben lifts the 100-pound barbell over his head 10 times in 10
seconds. Which student does the most work? ___same work___________ Which student delivers the most power? ____ben__________
Explain your answers.
Each lifts the same weight but ben does it much faster. Since we are worried about per second ben wins.
14. An often-used equation for power is Power = force*velocity Express an
understanding of the meaning of this equation by using it to explain what type of individuals would be the best choice for lineman on a football team.
Heavy people that can create a large force to
oppse.
Energy (CH 8 pg 105-111)
Definitions:
12.Potential energy is the ___potential_____________ energy of position
possessed by an object.
13.Kinetic energy is the energy of ____motion_____________.
14.The total amount of mechanical energy is merely the sum of the -___potential________ energy and the ___kinetic______________
energy. This sum is simply referred to as the total mechanical energy (abbreviated TME).
Calculate!
15.Read each of the following statements and identify them as having to do
with kinetic energy (KE), potential energy (PE) or both (B).
KE, PE or B? Statement:
KE i) If an object is at rest, it certainly does NOT possess this form of
energy. PE j) Depends upon object mass and
object height.
KE k) The energy an object possesses due to its motion.
B l) The amount is expressed using the
unit joule (abbreviated J).
PE m) The energy stored in an object due
to its position (or height).
PE n) The amount depends upon the arbitrarily assigned zero level.
KE o) Depends upon object mass and
object speed.
PE p) If an object is at rest on the ground
(zero height), it certainly does NOT possess this form of energy.
16.A toy car is moving along with 0.40 joules of kinetic energy. If its speed
is doubled, then its new kinetic energy will be _______. a. 0.10 J
b. 0.20 J c. 0.80 J
d. 1.60 J e. still 0.40 J
17.A young boy's glider is soaring through the air, possessing 0.80 joules of
potential energy. If its speed is doubled and its height is doubled, then the new potential energy will be _______.
a. 0.20 J b. 0.40 J c. 1.60 J
d. 3.20 J e. still 0.80
18.Which would ALWAYS be true of an object possessing a kinetic energy
of 0 joules? a. It is on the ground.
b. It is at rest. c. It is moving on the ground
d. It is moving. e. It is accelerating.
f. It is at rest above ground level g. It is above the ground.
h. It is moving above ground level. 19.Which would ALWAYS be true of an object possessing a potential
energy of 0 joules?
a. It is on the ground. b. It is at rest.
c. It is moving on the ground d. It is moving. e. It is accelerating.
f. It is at rest above ground level g. It is above the ground.
h. It is moving above ground level. 20.Calculate the kinetic energy of a 5.2 kg object moving at 2.4 m/s.
KE= ½ mv2
KE= ½ (5.2 kg) (2.4 m/s)2 =15 J
21. Calculate the potential energy of a 5.2 kg object positioned 5.8 m above
the ground.
PE=mgh
PE=5.2 kg*9.81 m/s2 *5.8m= 296 Nm
22. Calculate the speed of a 5.2 kg object that possesses 26.1 J of kinetic energy.
KE= ½ mv2
KE= ½ (5.2 kg) (x m/s)2 =26.1 J
x m/s = √26.1 J
½ (5.2 kg)= 3.17 m/s