Name ____________________________________________________________ACTIVITY #1: HOW FAST IS IT GOING?

“It’s the bottom of the 9th inning and Lynchburg’s best hitter is at bat with one last chance to tie the game. Here’s the pitch … it’s a fast ball down the middle. The slugger swings … it’s a high fly ball down the right field line … its caught! The Blue Rocks win the game.“

In baseball, a pitcher’s ability to throw a baseball fast and accurately can determine how successful he is in the sport. A pitcher sometimes throws a baseball at great speeds, while at other times he intentionally throws the ball at much slower speeds to confuse the batter. Speed is very important in the game of baseball, as it is in most sports.

What are three other sports where speed is important . . . tell how.

_________________________________________________________

_________________________________________________________

_________________________________________________________

The speed of an object tells how fast a moving object is traveling.

In this activity, you will be presented with a task to calculate the speed of a motorized buggy as it moves across the floor. You will have to determine what you must measure, how to measure it, and how you will use those measurements to calculate the speed of the buggy.

How could you measure speed? _______________________ ___________________________________________________

What things must you control in this type of experiment? ___________________________________________________

Can you give other examples where speed is very important? _________________________________________

_________________________________________

GOALS: In this lab activity, you will …

Design and conduct an experiment to determine the speed of a moving object (a buggy).

Compare the speeds of two moving objects qualitatively (which is faster, which is slower) and quantitatively (speed and how much faster does one object move than the other).

© 2006-2007 Delaware Science Coalition / Delaware Dept of Education1

ANTICIPATION: WHAT DOES METERS PER SECOND MEAN? __________________________________________________________________________________________________________________________________________ACTIVITY OVERVIEW: A synopsis of this lesson is as follows…

You will be asked to devise an experiment to determine the speed of a red motorized buggy and a blue one. You must then carry out your planned investigation, collect data, and communicate the results of your investigation to the rest of the class.

MAKING SENSE OF MOTION…

Which Object Moves Faster? The location of a moving object is always changing. When you roll a ball across the floor it starts near your feet. Soon, it ends up across the room from you. How fast was the ball traveling when it crossed the room? Speed is the word that people use to describe how quickly an object moves. In this activity we will learn that the speed of an object tells us how far the object moves every second (or hour). The object’s speed can also be used to determine how much time is needed for the object to travel a known distance. Many times we use speed to compare the motion of moving objects.

What is speed?

________________________________________________________________________

What two things can the speed of an object tell us?

o ___________________________________________________________________

o ___________________________________________________________________

Have you ever said to a classmate, “I can run faster than you?” Running a race gives us a chance to see speed in action. It is fun to start the race and get ahead of the other runners. When you run a race it isn’t hard to figure out which runner moves with the greatest speed. The runner with the greatest speed will cross the finish line first.

Remember making the K’NEX cars? We learned that when two cars went the same distance, the faster car was the one that traveled the distance in the least time. We also had a different kind of race. If one car was moving at a greater speed than another car, the faster car went a greater distance in the same amount of time.

Here is an example. Let’s say you and your friend are in different cars. The car you are in moves faster than the one your friend is in. If you both start at the same place, and ride in your cars for an hour, what will happen?

© 2006-2007 Delaware Science Coalition / Delaware Dept of Education2

_________________________________________ You will travel further than your friend because your car was moving with a greater speed. Races tell us which object moves faster, but sometimes we need to know more about the speed of a car.

Prediction: How could you find the actual speed of each car?

___________________________________________________________________________

___________________________________________________________________________

Constant Speeds and Average Speeds Finding the speed of moving objects is important. How do race officials decide the starting

positions for a big race? The drivers ‘qualify’ for the best starting positions by driving as fast as possible in qualifying laps on the racetrack.

All the cars travel the same distance and only one car can go around the track at a time during qualifying. So how do the race officials decide which cars travel with the greatest speed? The officials do what we are going to do; they make special measurements and use math skills to calculate speeds. First they measure the distance that the cars travel. Then, using a timer, they measure the time it took the car to travel that distance. These two measurements, distance and time, are used to find a car’s speed.

What two measurements are used to find the speed of a car?

________________ and ________________Is the car’s speed the same the whole way around the track? If the speed of a car remains the

same, the car moves with a constant speed. Objects that move with constant speed do not speed up or slow down. This does not usually happen. Almost always, an object will speed up and slow

down while traveling from one point to another. The race cars are good examples of this. There are curves and straight parts on a racetrack. Does the car travel as fast on a curved part of the track as it does on a straight part? Of course not! The car can move fast on the straight parts of the track, but must move slower on the curved parts. That is why when we talk about the car’s speed around the track we call it an average speed. This is because we know the car is not always moving at the same speed all the way around the track.

The average speed is a number that tells us how fast the car would be moving if its higher speeds and lower speeds were averaged out to a single speed. In fact, the average speed of the car can be used to calculate how far the car will travel or how long it takes to complete a trip. Average speeds are very useful because they can replace the complicated changing speeds when predicting the motion of a car or other moving objects.

What is average speed? _______________________________________________________

____________________________________________________________________________

What can average speed be used to calculate?o ______________________________________________________________________

o ______________________________________________________________________

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What is the difference between average speed and constant speed? __________________

_____________________________________________________________________________

Suppose you travel to the store in your car and your average speed for the trip is 30 miles/hr. Does this mean the car is moving with a constant speed of 30 miles/hour for the entire trip? No, the car was probably traveling slower than 30 miles/hour for parts of the trip and faster than 30 miles/hour for other parts. An average speed of 30 miles/hour means the car would take one hour to travel a distance of 30 miles. A car can have an average speed of 30 miles/hour even if it does not travel for 30 miles.

Question: Suppose the store was only 15 miles from your home. If your average speed was 30 miles/hour, how much time would the trip from your home to the store take? Show your work: Hint: Could you use a ratio table?

If the average speed of a car does not tell us the car’s exact speed on the straight parts, curved parts or any other part or the road, what do speed limit signs mean? Is a 55 mile/hour speed limit an average speed? Does it mean a car can travel faster than 55 miles/hour part of the time as long as its average speed is not more than 55 miles/hour?

Before you read on . . . What do you think speed limit signs mean? ________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

A 55 miles/hour speed limit means that the cars may not travel faster that 55 miles/hour at all. Drivers could receive speeding tickets if their cars travel faster than 55 miles/hour (even for only a short distance). Speed limits are posted for safety reasons.

Later in your middle school studies you will learn that every moving object has energy. Cars moving with too much energy can be dangerous. By limiting a car’s speed we also limit the energy of the car. That is the reason for posting speed limits.

© 2006-2007 Delaware Science Coalition / Delaware Dept of Education4

Let’s Investigate …

Determining the Speed of a Buggy

Materials : stopwatch meter stick some tape

a marking pen two motorized buggies: red and blue

Your task is to use the above materials to determine the speed of each buggy. Write at least three ideas* of how your group could determine the speed of each buggy:

1. 2. 3.

*After class discussion, we will determine which procedure we will all use in the investigation.

Conduct the experiment following these procedures:

_____________________________________________________________________________

_____________________________________________________________________________

_____________________________________________________________________________

_____________________________________________________________________________

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_____________________________________________________________________________

Make careful observations and record your data in the data table below.

Formula for Average Speed : S avg = Distance divided by time - S = d t

For each trial, the buggy will be traveling a distance of 100 centimeters.

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TrialsTimes (seconds)

Blue buggy Red buggy

Calculate the average speed of each buggy - Show your work

Trial #1 Blue Buggy: S = Distance Time

S = d -_____ T -

S = ____cm/s*

Red Buggy: S = Distance time

S = d - _____ T -

S = ____cm/s*

Trial #2

Trial #3

Trial #4

Trial #5

Average Time

(Will be used in the formula for Average Speed)

Add up the times for the trials, divide by 5

___________

Add up the times for the trials, divide by 5

___________

*centimeters per second

Write a conclusion for your results:

______________________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________

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Investigation Reflection:

1. Your calculated speed for each buggy is given in centimeters per second (cm/s). a. Compare the speeds of the two buggies and determine which buggy traveled with the

greatest speed. _______________________________________________________

2. Explain what the unit cm/s means:_________________________________________________________________________

_________________________________________________________________________

3. How much faster was one buggy moving when compared to the other buggy? Use both quantitative (numbers) and qualitative data (descriptions) to support your answer.

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

Summary of Activity …Write a concise summary of this activity.

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Be sure to address the following questions and use both qualitative and quantitative data to support your responses. How did you determine the speed of the buggy? What were the results of your investigation?

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

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Applying what you have learned …1. A group of astronomers discover that a small meteor has just passed the Moon and

is headed straight for Earth. The Moon is 400,000 kilometers away. The astronomers figure the average speed of the meteor is 4 km/s.

Using the data from the astronomers, how much time do we have to prepare before the meteor impact occurs?

o Show your work: What calculations did you make?

Investigating Further … As you read, underline/highlight key terms / important details SPEED LIMITS IN OUR DAILY LIVES …

Speed limits are all around us. In towns and cities, cars are expected to travel at speeds no greater than 25 miles per hour (mph). On highways, the speed limit is often 55 mph and on interstate

© 2006-2007 Delaware Science Coalition / Delaware Dept of Education8

highways it is typically set at 65 mph. Speed limits do not only apply to moving automobiles though.

For many years, it was thought that traveling faster than the speed of sound would destroy an aircraft and its pilot. Many people argued that it wasn’t even possible to reach such a speed. On October 14, 1947 Captain Charles Yeager piloted the Bell X-1 aircraft past the sound barrier and ushered in a new era of airplane speed. Today traveling faster than the speed of sound is a common occurrence for any fighter pilot. It is possible for jets to go 2x, 3x and even in some tests, 10x the speed of sound.

The speed of sound is commonly referred to as Mach 1. The actual speed of sound varies with air temperature and

altitude, but is roughly 750 miles/hour. Captain Yeager’s X-1 aircraft, nicknamed “Glamorous Glennis”, now resides in the care of the Smithsonian Institution.

The speed of light is even more astonishing. It is believed to be the ultimate speed limit of the universe. The speed of light is an awesome 186,000 miles per second! The speed of sound and the speed of light are very different. It is this difference that explains why we see lightning and then seconds later we hear the thunder when the two occur at the same time. You can also experience this effect on the Fourth of July while watching

fireworks displays from a distance.

On the following page, create a graphic organizer to compare light and sound.Compare Light and Sound:

© 2006-2007 Delaware Science Coalition / Delaware Dept of Education9

Velocity NOTES In physics, they have very specific (and ____________________)

meanings.

Speed is ______________________________________________________

Velocity is ________________________________________________________________________________________________________________

Use velocity in a sentence that shows you know the definition:

_____________________________________________________________________________

_____________________________________________________________________________

CONNECTIONS/Big Ideas Review for Activity 1Scientific Content

The _______________ of an object tells us of how quickly the object moves from one point to another.

The speed tells us how far the object travels in a given amount of __________. The speed allows us to calculate how much time the object will need to travel a

certain __________________________.

An object traveling with a _____________________ speed moves with a single unchanging speed. Constant speed motion is ________. Usually the speed of an object will change during its motion.

When the speed of an object changes, its __________________ speed can be a useful way to express how fast the object moves.

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The average speed can replace the actual changing speed when calculating how __________ an object travels or how much _______________ it takes the object to travel a certain distance.

The average speed of an object can be calculated by dividing the ________________ it travels by the amount of ______________ needed to move through this distance. This relationship can be expressed by the equation

Average speed = distance traveled / time needed (total distance divided by total time )

or Savg = D / T

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Activity 1: How Fast is it Going? Name ______________________________ Speed Problems Date __________________ CORE _____

What is the formula for Average Speed?

____________________________________

Show the math used to answer these questions.1. Bonnie rode her skateboard 200 meters (m) in 30 seconds (s). Raul rode his unicycle 300 m in 50 s.

Who traveled faster? __________

How much faster? ________

2. A chipmunk can run 5 m/s. A fox can run 8 m/s. If the chipmunk and fox start running at the same time, will the chipmunk make it to the safety of its burrow in time? ________

Explain: ___________________________________

_____________________________________________

3. Rita flew from Los Angeles to Boston to visit her aunt, a distance of 4000 km. The trip took 5 hours (h).

What was the average speed of the jet?

___________________________________

4. A champion jumping frog can jump 2.5m every 4s.

What is the jumping frog’s average speed?

Challenge Questions

1. Rosita started riding her bike 3 km to her friend Gina’s place at exactly the same time Gina started skating to Rosita’s house. Gina, of course, wasn’t home, so Rosita rode back home. The two girls arrived at Rosita’s house at the same time. It took Rosita 30 minutes

© 2006-2007 Delaware Science Coalition / Delaware Dept of Education

Work space for #1

Work space for #2

Work space for #3

Work space for #4

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to ride to Gina’s and back. How fast did Gina skate?

2. A hiker wanted to hike to a lake 26 km from the end of the road. She started at 6 a.m. and walked steadily until 9:00 a.m. She stopped for a 1-hour rest and then continued until she stopped for 1.5 h to have lunch. She took only one 0.5 h rest in the afternoon and arrived at the lake at 7:00 p.m.

a. What was the hiker’s average speed from the end of the road to the lake?

b. What was the hiker’s average speed during the time she was actually hiking?

Hand out as students enter the classroom. Upon a given signal, students find other students with same word to discuss what they know in a “Rally Robin”.

ConstantSpeed

AverageSpeed

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Velocity SpeedDistance divided by

Time Non-Constant

SpeedMeasuring

SpeedConstant

SpeedAverageSpeed

Velocity SpeedDistance divided by

Time Non-Constant

SpeedMeasuring

Speed

velocity is both© 2006-2007 Delaware Science Coalition / Delaware Dept of Education

14

speed and direction

average speed is distance

divided by time

constant speedis unchangin

gnonconsta

ntspeed

does © 2006-2007 Delaware Science Coalition / Delaware Dept of Education

15

change

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