Physics C Practice
A physics test on Momentum, Center of Mass, and Simple Harmonic Oscillation
- 1.In simple harmonic motion, the restoring force must be proportional to the:
- A.
Amplitude
- B.
Frequency
- C.
Velocity
- D.
Displacement
- E.
Displacement squared
- 2.An oscillatory motion must be simple harmonic if:
- A.
The amplitude is small
- B.
The potential energy is equal to the kinetic energy
- C.
The motion is along the arc of a circle
- D.
The acceleration varies sinusoidally with time
- E.
The derivative, dU/dx, of the potential energy is negative
- 3.In simple harmonic motion, the magnitude of the acceleration is:
- A.
Constant
- B.
Proportional to the displacement
- C.
Inversely proportional to the displacement
- D.
Greatest when the velocity is greatest
- E.
Never greater than g
- 4.A particle is in simple harmonic motion with period T. At time t = 0 it is at the equilibrium point. Of the following times, at which time is it furthest from the equilibrium point?
- A.
0.5T
- B.
0.7T
- C.
T
- D.
1.4T
- E.
1.5T
- 5.A particle moves back and forth along the x axis from x = −xm to x = +xm, in simple harmonic motion with period T. At time t = 0 it is at x = +xm. When t = 0.75T:
- A.
It is at x = 0 and is traveling toward x = +xm
- B.
It is at x = 0 and is traveling toward x = −xm
- C.
It is at x = +xm and is at rest
- D.
It is between x = 0 and x = +xm and is traveling toward x = −xm
- E.
It is between x = 0 and x = −xm and is traveling toward x = −xm
- 6.An object attached to one end of a spring makes 20 complete oscillations in 10 s. Its period is:
- A.
2 Hz
- B.
10 s
- C.
0.5 Hz
- D.
2 s
- E.
0.50 s
- 7.In simple harmonic motion, the magnitude of the acceleration is greatest when:
- A.
The displacement is zero
- B.
The displacement is maximum
- C.
The speed is maximum
- D.
The force is zero
- E.
The speed is between zero and its maximum
- 8.It is impossible for two particles, each executing simple harmonic motion, to remain in phase with each other if they have different:
- A.
Masses
- B.
Periods
- C.
Amplitudes
- D.
Spring constants
- E.
Kinetic energies
- 9.Which one of the following statements is true?
- A.
The center of mass of an object must lie within the object
- B.
All the mass of an object is actually concentrated at its center of mass
- C.
The center of mass of an object cannot move if there is zero net force on the object
- D.
The center of mass of a cylinder must lie on its axis
- E.
None of the above
- 10.A certain spring elongates 9.0 mm when it is suspended vertically and a block of mass M is hung on it. The natural angular frequency of this block-spring system:
- A.
Is 0.088 rad/s
- B.
Is 33 rad/s
- C.
Is 200 rad/s
- D.
Is 1140 rad/s
- E.
Cannot be computed unless the value of M is given
- 11.The center of mass of a uniform disk of radius R is located:
- A.
On the rim
- B.
A distance R/2 from the center
- C.
A distance R/3 from the center
- D.
A distance 2R/3 from the center
- E.
At the center
- 12.Block A, with a mass of 4 kg, is moving with a speed of 2.0 m/s while block B, with a mass of 8 kg, is moving in the opposite direction with a speed of 3 m/s. The center of mass of the two block-system is moving with a velocity of:
- A.
1.3 m/s in the same direction as A
- B.
1.3 m/s in the same direction as B
- C.
2.7 m/s in the same direction as A
- D.
1.0 m/s in the same direction as B
- E.
5.0 m/s in the same direction as A
- 13.At the same instant that a 0.50-kg ball is dropped from 25 m above Earth, a second ball, with a mass of 0.25 kg, is thrown straight upward from Earth’s surface with an initial speed of 15 m/s. They move along nearby lines and pass each other without colliding. At the end of 2.0 s the height above Earth’s surface of the center of mass of the two-ball system is:
- A.
2.9 m
- B.
4.0 m
- C.
5.0 m
- D.
7.1 m
- E.
10.4 m
- 14.At the same instant that a 0.50-kg ball is dropped from 25 m above Earth, a second ball, with a mass of 0.25 kg, is thrown straight upward from Earth’s surface with an initial speed of 15 m/s. They move along nearby lines and pass without colliding. At the end of 2.0 s the velocity of the center of mass of the two-ball system is:
- A.
11 m/s, down
- B.
11 m/s, up
- C.
15 m/s, down
- D.
15 m/s, up
- E.
20 m/s, down
- 15.A 0.20-kg object attached to a spring whose spring constant is 500 N/m executes simple harmonic motion. If its maximum speed is 5.0 m/s, the amplitude of its oscillation is:
- A.
0.0020 m
- B.
0.10 m
- C.
0.20 m
- D.
25 m
- E.
250 m
- 16.A 0.25-kg block oscillates on the end of the spring with a spring constant of 200 N/m. If the system has an energy of 6.0 J, then the maximum speed of the block is:
- A.
0.06 m/s
- B.
0.17 m/s
- C.
0.24 m/s
- D.
4.9 m/s
- E.
6.9 m/s
- 17.At the same instant that a 0.50-kg ball is dropped from 25 m above Earth, a second ball, with a mass of 0.25 kg, is thrown straight upward from Earth’s surface with an initial speed of 15 m/s. They move along nearby lines and pass without colliding. At the end of 2.0 s the magnitude of the acceleration of the center of mass of the two-ball system is:
- A.
0.25g
- B.
0.50g
- C.
0.75g
- D.
G
- E.
G/0.75
- 18.A 640-N hunter gets a rope around a 3200-N polar bear. They are stationary, 20 m apart, on frictionless level ice. When the hunter pulls the polar bear to him, the polar bear will move:
- A.
1.0 m
- B.
3.3 m
- C.
10 m
- D.
12 m
- E.
17 m
- 19.A 2.0-kg block is attached to one end of a spring with a spring constant of 100 N/m and a 4.0-kg block is attached to the other end. The blocks are placed on a horizontal frictionless surface and set into motion. At one instant the 2.0-kg block is observed to be traveling to the right with a speed of 0.50 m/s and the 4.0-kg block is observed to be traveling to the left with a speed of 0.30 m/s. Since the only forces on the blocks are the force of gravity, the normal force of the surface, and the force of the spring, we conclude that:
- A.
The spring is compressed at the time of the observation
- B.
The spring is not compressed at the time of observation
- C.
The motion was started with the masses at rest
- D.
The motion was started with at least one of the masses moving
- E.
The motion was started by compressing the spring
- 20.
- A.
Particles of the system must be exerting forces on each other
- B.
The system must be under the influence of gravity
- C.
The center of mass must have constant velocity
- D.
A net external force must be acting on the system
- E.
None of the above
- 21.
- A.
The force of your foot on the accelerator
- B.
The force of friction of the road on the tires
- C.
The force of the engine on the drive shaft
- D.
The normal force of the road on the tires
- E.
None of the above
- 22.An object on the end of a spring is set into oscillation by giving it an initial velocity while it is at its equilibrium position. In the first trial the initial velocity is v0 and in the second it is 4v0. In the second trial:
- A.
The amplitude is half as great and the maximum acceleration is twice as great
- B.
The amplitude is twice as great and the maximum acceleration is half as great
- C.
Both the amplitude and the maximum acceleration are twice as great
- D.
Both the amplitude and the maximum acceleration are four times as great
- E.
The amplitude is four times as great and the maximum acceleration is twice as great
- 23.Bullets from two revolvers are fired with the same velocity. The bullet from gun #1 is twice as heavy as the bullet from gun #2. Gun #1 weighs three times as much as gun #2. The ratio of the momentum imparted to gun #1 to that imparted to gun #2 is:
- A.
2:3
- B.
3:2
- C.
2:1
- D.
3:1
- E.
6:1
- 24.Force:
- A.
Equals the negative integral (with respect to distance) of the potential energy function
- B.
Is the ability to do work
- C.
Is the rate of change of doing work
- D.
Equals the time rate of change of momentum
- E.
Has dimensions of momentum multiplied by time
- 25.A cart loaded with sand slides forward along a horizontal frictionless track. As the cart moves, sand trickles out at a constant rate through a hole in the back of the cart. The acceleration of the cart is:
- A.
Constant and in the forward direction
- B.
Constant and in the backward direction
- C.
Variable and in the forward direction
- D.
Variable and in the backward direction
- E.
Zero
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