Journals

SPRING PHYSICS 2016

Journal #1 1/7/20161. 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 0.260 m and the time for one revolution is 0.0330 s, how fast is the barrel spinning?

49.5 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.

5.12 N

DO NOT ROUND UNTIL THE END.

Journal #2 1/11/20161. 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 1/13/20161. 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 1/20/2016• 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 1/21/20161. In what two ways can you increase power?

increase work done or decrease the time

2. Renatta Gass is out with her friends when her car breaks down. Together 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 1/22/2016On 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 2/1/20161. 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. An object is moving 2.5 m/s when it strikes the ground. From what height was the object dropped?

hi = 0.32 m

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 2/5/2016

• 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 2/8/2016

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 2/9/20161. You 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. Determine the time delay between a bat’s sending of a pulse and the return of its reflection from an object located 12.5 m away. 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 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 #11 2/10/20161. 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 #12 2/22/2016

•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 #13 2/24/20161. Sound travels at 5600 m/s through a steel rod. If the

frequency of the wave is 2480 Hz, what is the wavelength of the wave?

λ = 2.3 m

2. What is the frequency of a sound made by a violin string with a wavelength of 0.55 m if the wave is traveling at 350 m/s?

f = 640 Hz

3. A wave on the lake has a wavelength of 2 m and has a frequency of 25 Hz. What is the speed of the wave?

v = 50 m/s

Journal #14 2/26/2016

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 #15 2/29/2016

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 #16 3/4/20161. 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 #17 3/7/20161. 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 #18 3/8/20161. 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 #19 3/10/2016

Use the diagrams below to answer questions 1 and 2. The dotted lines represent the stationary object. The greater the shift, the faster the motion.

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

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

B

A

Journal #20 3/11/20161. If an object absorbs cyan light and a yellow light source is

shined on the object, what color will it appear?

A. Blue

B. Yellow

C. Red

D. Black

2. An object looks cyan under white light. What color will it appear if a red light shines on it?

A. Blue

B. Red

C. Green

D. Black

Journal #21 3/14/20161. 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. How would you orient polarizing filters to block most all of the light from a source?

at a 90 degree angle to one another

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!)