Name: ___________________________________    Date: ______________



1.
A 1.5 kg crate falls from a height of 2.0 m onto an industrial spring scale with a spring constant of 1.5 × 105 N/m. At its greatest compression the reading on the scale is:
A.
15 N
B.
30 N
C.
1.5 × 103 N
D.
2.1 × 103 N
E.
3.0 × 103 N


2.
A boy holds a 40-N weight at arm's length for 10 s. His arm is 1.5 m above the ground. The work done by the force of the boy on the weight while he is holding it is:
A.
0
B.
6.1 J
C.
40 J
D.
60 J
E.
90 J


3.
An object of mass 1 g is whirled in a horizontal circle of radius 0.5 m at a constant speed of 2 m/s. The work done on the object during one revolution is:
A.
0
B.
1 J
C.
2 J
D.
4 J
E.
16 J


4.
A 0.50-kg block attached to an ideal spring with a spring constant of 80 N/m oscillates on a horizontal frictionless surface. When the spring is 4.0 cm longer than its equilibrium length, the speed of the block is 0.50 m/s. The greatest speed of the block is:
A.
0.23 m/s
B.
0.32 m/s
C.
0.55 m/s
D.
0.78 m/s
E.
0.93 m/s


5.
A rectangular block is moving along a frictionless path when it encounters the circular loop as shown. The block passes points 1,2,3,4,1 before returning to the horizontal track. At point 3:
A.
its mechanical energy is a minimum
B.
the forces on it are balanced
C.
it is not accelerating
D.
its speed is a minimum
E.
it experiences a net upward force


6.
As a particle moves along the x axis it is acted by a conservative force. The potential energy is shown below as a function of the coordinate x of the particle. Rank the labeled regions according to the magnitude of the force, least to greatest.
A.
AB, BC, CD
B.
AB, CD, BC
C.
BC, CD, AB
D.
BC, AB, CD
E.
CD, BC, AB


7.
A stream of gas consists of n molecules. Each molecule has mass m and speed v. The stream is reflected elastically from a rigid surface as shown. The magnitude of the change in the total momentum of the stream is:
A.
2mnv
B.
2mnv sin 30°
C.
mnv sin 30°
D.
mnv cos 30°
E.
mnv


8.
The center of mass of a system of particles obeys an equation similar to Newton's second law where:
A.
is the total internal force and m is the total mass of the system
B.
is the total internal force and m is the mass acting on the system
C.
is the total external force and m is the total mass of the system
D.
is the force of gravity and m is the mass of Earth
E.
is the force of gravity and m is the total mass of the system


9.
Cart A, with a mass of 0.2 kg, travels on a horizontal air track at 1 m/s and hits cart B, which has a mass of 0.4 kg and is initially at rest. After the collision the center of mass of the two cart system has a speed in m/s of:
A.
zero
B.
0.33 m/s
C.
2.3 m/s
D.
2.5
E.
5.0 m/s


10.
A light rope passes over a light frictionless pulley attached to the ceiling. An object with a large mass is tied to one end and an object with a smaller mass is tied to the other end. Starting from rest the heavier object moves downward and the lighter object moves upward with the same magnitude acceleration. Which of the following statements is true for the system consisting of the two objects?
A.
The center of mass remains at rest.
B.
The net external force is zero.
C.
The velocity of the center of mass is a constant.
D.
The acceleration of the center of mass is g, downward.
E.
None of the above statements are true.


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