Journals

SPRING PHYSICS 2015

Journal #1 1/8/2015 1. During the spin cycle of a washing machine, the clothes

stick to the outer wall of the barrel as it spins. If the radius of the barrel is 0.26 m and the time for one revolution is 0.033 s, how fast is the barrel spinning?

49 m/s

2. A battery-powered plane is suspended from a string and flying in a horizontal circle. The plane makes a complete circle every 2.15 seconds. The radius of the circle is 0.950 m. If the plane has a mass of 0.631 kg determine the centripetal force acting on the plane.

5.11 N

DO NOT ROUND UNTIL THE END.

Journal #2 1/9/2015 1. A 45 kg merry-go-round worker stands 6.3 m from

the center of the ride and it takes 9.65 s for the ride to make one revolution.

A. What is the centripetal force acting on the worker?

120 N

B. What type of force provides the centripetal force?

friction

Journal #3 1/13/2015 1. Determine the force of gravitational attraction between the

earth (m = 5.98 x 1024 kg) and a 70.0 kg physics student if the student is in an airplane at 40000 feet above earth's surface. This would place the student a distance of 6.39 x 106 m from earth's center.

684 N

2. Suppose that two objects attract each other with a gravitational force of 40N. If the distance between the two objects is doubled, what is the new force of attraction between the two objects?

10 N

Journal #4 1/21/2015 • Use the following terms to complete the statements below:

• Potential energy

• Kinetic energy

• Work

• Conservation of energy

• Power

1. is the energy due to position or stored energy.

2. is the rate at which work is done.

3. means that energy can not be created or destroyed.

4. is the energy transferred when a force is applied over a certain distance.

5. is the energy of motion.

Potential energy

Power

Conservation of energy

Work

Kinetic energy

Journal #5 1/23/2015 1. In what two ways can you increase power?

increase work done or decrease the time

2. Renatta Gass is out with her friends. Misfortune occurs and Renatta and her friends find themselves getting a workout. They apply a cumulative force of 1080 N to push the car 218 m to the nearest fuel station. Determine the work done on the car.

235,000 J

3. During practice, Fast Eddie runs up the stairs, elevating his 102 kg body a vertical distance of 2.29 meters in a time of 1.32 seconds at a constant speed. Determine the power he generated.

1,730 W

Journal #6 1/26/2015 On a roller coaster,

1. Which has the greatest affect on speed, height or direction of motion (uphill or downhill)?

height

2. How does speed relate to height?

greater height = greater final speed at the lowest height

3. Where do you move the fastest? Why?

D because it is the lowest point (PE min = KE max)

C

D

A

B

Journal #7 1/27/2015 1. Calculate the speed of an object just as it strikes the ground if it is

dropped from a height of 15 m.

vf = 17 m/s

2. What happens to the potential energy of an object if…

A. the mass of the object is doubled?

potential energy doubles

B. the height of the object is doubled?

potential energy doubles

C. both the mass and the height are doubled?

potential energy quadruples

3. What happens to the kinetic energy of an object if…

A. the mass of the object is doubled?

kinetic energy doubles

B. the speed of the object is doubled?

kinetic energy quadruples

Journal #8 2/6/2015

• What type of waves are represented in the diagram below?

• What is the main difference between these two types of waves?

Transverse waves have perpendicular particle motion and longitudinal have parallel particle motion to wave direction.

(a)

(b)

Journal #9 2/9/2015

Water waves in a lake travel 3.4 m in 1.8 s. The period of oscillation is 1.1 s.

A. What is the speed of the water waves? (HINT: Use your old equation for speed.)

1.9 m/s

B. What is the frequency of the waves?

0.91 Hz

C. What is the wavelength?

2.1 m

Journal #10 2/11/2015

•What factor had the biggest effect on the period of a pendulum?

The length of the string has the greatest effect on the period of the pendulum. The longer the string, the longer the period.

•Can you explain why the others had almost no effect at all?

Because gravity pulls on all objects equally, mass nor angle have a great effect on the period of a pendulum.

Journal #11 2/18/2015 1. Jerome and Claire are doing the Period of a Pendulum Lab. They

observe that a pendulum makes exactly 10 complete back and forth cycles of motion in 21.8 seconds. Determine the period of the pendulum.

2.18 s

2. Microbats use echolocation to navigate and hunt. Determine the time delay between the bat’s sending of a pulse and the return of its reflection from an `object located 12.5 m away. Approximate the speed of the sound waves as 345 m/s.

0.0725 s

3. A marine weather station detects waves which are 9.28 meters long and 1.65 meters high and travel a distance of 50.0 meters in 21.8 seconds. Determine the speed and the frequency of these waves.

v = 2.29 m/s and f = 0.247 Hz

Journal #12 3/2/2015 1. Label the following in the diagram below: amplitude, wavelength,

crest, and trough.

2. How many wavelengths are shown in the diagram?

2.5

3. Which variable has the most effect on the period of a pendulum: length, mass, or amplitude?

length

Journal #13 3/3/2015

1. What is the highest harmonic shown in the diagram?

7th

2. If the length of the string is 5 m, what is the wavelength of the 5th harmonic?

2 m

3. If the fundamental frequency is 15 Hz, what is the frequency of the 3rd harmonic?

45 Hz

Journal #14 3/4/2015

• Use the information provided in the demo and the diagram to the right to complete the following questions.

1. How many antinodes appear in the diagram?

4

2. If the frequency of the first harmonic is 10.0 Hz, what is the approximate frequency of this wave?

40.0 Hz

3. If the frequency of the wave is increased, what will happen to the wavelength?

The wavelength will decrease.

Journal #15 3/10/2015 1. Of the following electromagnetic waves, which has the longest

wavelength?

A. Microwaves

B. Visible Light

C. Gamma Rays

D. X-rays

2. Light can have different colors because it can have different…

A. frequencies

B. wavelengths

C. energies

D. All of the above are true.

3. If an element’s spectral line has a wavelength of 432 nm, what is the frequency of that element’s spectral line? Approximately what color is this line?

f = 6.94 x 1014 Hz; approximately blue/violet

Journal #16 3/11/2015 1. The frequency of a beam of light is 4.80 x 1014 Hz. What

is the wavelength? What is the wavelength in nanometers?

λ = 6.25 x 10-7 m = 625 nm

2. As the frequency of light increases, what happens to wavelength?

As frequency increases, wavelength decreases.

3. What type of EM radiation has the highest frequency?

Gamma waves have the highest frequency.

4. What type of EM radiation has the longest wavelength?

Radio waves have the longest wavelength.

Journal #17 3/13/2015 1. Which color of light is produced by mixing red and blue

light?

A. white

B. cyan

C. yellow

D. magenta

2. When white light is shined on __________, two primary light colors are reflected and one primary light color is absorbed.

A. secondary pigment

B. primary pigment

C. both primary and secondary pigments

3. What are the three primary colors of light?

blue, red and green

4. What are the three primary colors of pigment?

cyan, magenta and yellow

Journal #18 3/16/2015 1. How would you orient polarizing filters to block most all of

the light from a source?

Use the diagrams below to answer questions 2 and 3. The dotted lines represent the stationary object. The greater the shift, the faster the motion.

2. Which diagram above shows a star that is moving the fastest TOWARD the Earth?

3. Which diagram above shows a star that is moving the slowest AWAY from the Earth?

perpendicular (90o to one another)

B

A

Journal #19 3/17/2015 1. When light falls on a soap bubble or on an oily

film, a spectrum of colors is observed. How is this spectrum formed?

interference of light waves

2. What is the term that describes when light waves are all oriented in one plane?

polarization

3. What is the term that describes when light waves bend around a barrier?

diffraction

4. Light takes 8.0 minutes to travel from the Sun to the Earth. How far away is the Sun from the Earth?

1.4 x 1011 m (about 93 million miles!)

Journal #20 3/23/2015 1. Label the following light

rays as either converging or diverging.

2. Label the following diagrams as either specular or diffuse reflection.

3. Label the following diagram with incident ray, reflected ray, angle of incidence, angle of reflection, and normal.

specular

diverging

diffuse

converging

reflected ray

angle of incidence

normal

incident ray

angle of reflection

Object

Placement/Mirror

Size of image

compared to size

of object

Real or Virtual Upright or Inverted

Plane Mirror

Between Concave

Mirror and f

At f of Concave

Mirror

Beyond f of

Concave Mirror

Convex Mirror

(anywhere)

Journal #21 3/25/2015

Object

Placement/Mirror

Size of image

compared to size

of object

Real or Virtual Upright or Inverted

Plane Mirror Same Virtual Upright

Between Concave

Mirror and f Enlarged Virtual Upright

At f of Concave

Mirror No Image No Image No Image

Beyond f of

Concave Mirror

Enlarged,

Reduced or Same

Size

Real Inverted

Convex Mirror

(anywhere) Reduced Virtual Upright

Journal #21 ANSWERS 3/25/2015

Journal #22 3/27/2015 1. If you know the focal length of a concave mirror, where

should you place an object so that its image is upright and larger compared to the object?

You should place the object between the focal point (f) and the mirror.

2. What type of image is formed in the above question?

The image is virtual.

3. Determine the image distance and image height for a 5.00 cm tall object placed 10.0 cm from a concave mirror having a focal length of 15.0 cm.

di = -30.0 cm and hi = 15.0 cm

Journal #23 3/30/2015 1. Refraction occurs when

A. light travels through the boundary of two media that have different densities.

B. light travels through the boundary of two media that have the same density.

C. the angle of incidence equals zero.

D. the angle of refraction equals zero.

2. In the figure below, light is traveling from a __________ dense medium to a __________ dense medium.

A. more, less

B. less, more

Journal #24 3/31/2015 Match the diagrams with the correct image description.

A. B.

1. virtual, upright, reduced B

2. real, inverted, same size A

3. Explain how no image is formed from a lens. No image is formed when an object is placed at the focal point of a convex lens.

Journal #25 4/14/2015 Complete the table below.

Quantity Definition Unit Symbol

Potential Difference

Current

Power

Resistance

Journal #25 4/14/2015 Complete the table below.

Quantity Definition Unit Symbol

Potential Difference the change in PE required for charge flow V V

Current the flow rate of electrons (charge) A I

Power the rate at which energy is transferred W P

Resistance property that determines charge flow Ω R

Journal #26 4/15/2015 Use the diagram below to answer the following questions.

1. What type of circuit is in the diagram?

series

2. What is the total resistance of the circuit?

60 Ω

3. What it the total current in the circuit?

2 A

Journal #27 4/16/2015 1. A roller coaster car rapidly picks up speed as it rolls down

a slope. As it starts down the slope, its speed is 4.0 m/s. But 3.0 seconds later, at the bottom of the slope, its speed is 22 m/s. Calculate the acceleration of the roller coaster.

a = 6.0 m/s2

2. Use the following velocity-time graph to calculate the acceleration for time intervals A, B and C.

A. 2 m/s2

B. 0 m/s2

C. -0.5 m/s2

Journal #28 4/21/2015 Label the following statements and diagrams as either series or parallel.

1. current remains constant

2.

3. voltage remains constant

4. resistance decreases as resistors are added so current increases

5.

6. voltage drops across each resistor

parallel

parallel

parallel

series

series

series

Journal #29 5/11/2015 Refer to the diagram below to answer questions 1-3.

1. What is the total resistance of the circuit?

8 Ω

2. What is the total current in the circuit? 3 A

3. What is the voltage drop across the 2 Ω resistor? 6 V

4. Describe the magnetic field created by the wire loop shown below. I

The magnetic field points toward you outside the loop and away inside the loop.