# Homework Help: Simple harmonic motion (4 questions)

1. Nov 12, 2004

### jin

1. A 4.0kg block is suspended from a spring with force constant of 500N/m. A 50g bullet
is fired into the block from directly below with a speed of 150m/s and is imbedded in
the bloack. (a) Find the amplitude of the resulting simple harmonic motion. (b) What
fraction of the original kinetic energy of the bullet appears as mechanical energy in the
harmonic oscillation?

2. Assume that you are examining the characteristics of the suspension system of a 2000kg
automobile. The suspension “sags” 10cm when the weight of the entire automobile is placed
on it. In addition, the amplitude of oscillation decreases by 50% during one complete
oscillation. Estimate the values of k and b for the spring and shock absorber system of one
wheel, assuming that one wheel supports 500kg.

3. A 2200lb car carrying four 180lb people drives over a rough “washboard” dirt road with
corrugations 13ft apart. The car bounces with maximum amplitude when its speed hits
10mi/h. The car now stops and the four people get out . By how much does the car rise
on its suspension owing to this decrease in weight?

4. A small mass with m = 100 grams is attached to a vertical string of length l = 2m in
the earth’s gravity. The mass swings back and forth with no loss of energy. The maximum
angle from the vertical is 45. This problem is not simple harmonic motion because the
maximum angle of displacement is not small. Find the velocity when the string is vertical,
 = 0. Find the tension in the string at  = 0. What is the velocity at  = 0 if you assume
simple harmonic motion?

need help studying for it..plz help!! thx

2. Nov 12, 2004