19 April 2013

Physics Homework Ch 13

1. A block of mass m = 0.55 kg is attached to a spring with a force constant 109 N/m is free to move on a frictionless, horizontal surface as in the figure below. The block is released from rest after the spring is stretched at distance A = 0.13 m. (Indicate the direction with the sign of your answer. Assume that the positive direction is to the right).

Spring stretched a distance of "A" with force constant of 109 N/m

a) At that instant, find the force on the block.
______ N

b) At that instant, find its acceleration
______ m/s2

2.The force constant of a spring is 165 N/m.

a) Find the magnitude of the force required to compress the spring by 4.20 cm from its unstretched length.
______ N

b) Find the magnitude of the force required to stretch the spring by 7.96 cm from its unstretched length.
______ N

3. A slingshot consists of a light leather cup containing a stone. The cup is pulled back against two parallel rubber bands. It takes a force of 15 N to stretch either one of these bands 1.0 cm.

a) What is the potential energy stored in the two bands together when a 44-g stone is placed in the cup and pulled back 0.11-m from the equilibrium position?
______ J

b) With what speed does the stone leave the slingshot?
______ m/s

4. A 10.0-g bullet is fired into, and embeds itself in, a 1.95-kg block attached to a spring with a force constant of 16.2 N/m and whose mass is negligible. How far is the spring compressed if the bullet has a speed of 300 m/s just before it strikes the block and the block slides on a frictionless surface? Note: You must use conservation of momentum in this problem because of the inelastic collision between the bullet and block.
______ m

5. A man enters a tall tower, needing to know its height. He notes that a long pendulum extends from the ceiling almost to the floor and that its period is 10.5 s.

a) How tall is the tower?
______ m

b) If this pendulum is taken to the moon, where the free-fall acceleration is 1.67 m/s2, what is the period there?
______ s

6. 10.03 A simple pendulum has a lenght of 52.1 cm and makes 83.8 complete oscillations in 2.00 min.

a) Find the period of the pendulum.
______ s

b) Find the value of g at the location of the pendulum.
______ m/s2

7. The sunusoidal wave shown in the figure below is traveling in the positive x-direction and has a frequency of 14.5 Hz.

Sinusoidal Wave 14.5 Hz

a) Find the amplitude.
_____ cm

b) Find the wavelength.
______ cm

c) Find the period
______ s

d) Find the speed of the wave
______ m/s

8. Light waves are electromagnetic waves that travel at 3.00 x 108 m/s. The eye is most sensitive to light having a wavelength of 5.50 x 107 m.

a) Find the frequency of this light wave.
_______ Hz
b) Find its period
_______ s

9. A circus performer stretches a tightrope between two towers. He strikes one end of the rope and sends a wave along it toward the other tower. He notes that it takes the wave 0.885 s to reach the opposite tower, 20.0 m away. If a 1.00-m length of rope has a mass of 0.360 kg, find the tension in the tightrope.
______ N

10. A piano string having a mass per unit length equal to 4.80 x 10-3 kg/m is under a tension of 1,450 N. Find the speed with which a wave travelson this spring.
______ m/s

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