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Physics 102
First Homework
Due Tuesday, Sept 17
Since the Honor Pledge is required on all assignments, all the homework in this course will be considered a single assignment, and you are asked to sign the following pledge to cover this and all future homework in this course:
"I pledge on my honor that I have not given or received any unauthorized assistance on this assignment/examination."

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Problems: (answer on this sheet)

1. According to its schedule, a Shuttle-UM bus runs perfectly regularly from Lot HH to the College Park Metro Station and back, taking 24 minutes to complete a round trip.

  1. Is this motion periodic?
     
  2. Is the motion sinusoidal? If not, what standard wave (text, p. 10) would more nearly describe the motion? Assume - unrealistically - the shuttle moves at a uniform speed and is not held up by traffic lights.
     
  3. What is the period, in seconds?
     
  4. What is the frequency, in Hertz? (use "scientific notation", that is, 10 to a suitable power, to express this rather small number)
2. There is actually more than one bus running on the Shuttle-UM route
  1. Suppose a second bus leaves lot HH 12 minutes after the first one. What is the phase relationship between the motions of the two buses?
     
  2. The actual schedule shows the next bus leaving 8 minutes after the first one. What is the phase difference (in degrees) between the two?
3. Flashes of light are produced by placing a light source behind a fan. The fan has four blades rotating at 500 rpm, which "chop" the light.
  1. What is the frequency with which the light is being "chopped"?
     
  2. At right, plot the light intensity emerging from the fan versus time.
4. a. Below the graph of problem 3, draw a graph of motion that decreases in both frequency and amplitude as time progresses:

    b. Is this damped harmonic motion? Why or why not?


5. Circle the letter of the phenomenon described below if it is
an example of resonance:
  1. A cork bobbing up and down in waves in the water
  2. Grandpa rocking in his favorite rockin chair
  3. A singer hitting a high note and shattering a glass
  4. People at a rock concert stomping their feet in rythm with the music
  5. Floor of auditorium vibrating and cracking due to stomping of audience in d.
  6. A rattle in your car that occurs while idling but stops as the motor increases speed.