Classical Mechanics Answers

A slender uniform rod 100.00 cm long is used as a meter stick. Two parallel axes that are perpendicular to the rod are considered. The first axis passes through the 50-cm mark and the second axis passes through the 30-cm mark. What is the ratio of the moment of inertia through the second axis to the moment of inertia through the first axis?
1 : I2/I1 = 1.5
2 : I2/I1 = 1.7
3 : I2/I1 = 1.9
4 : I2/I1 = 2.1
5 : I2/I1 = 2.3

A ball is tied to the end of a cable of negligible mass. The ball is spun in a circle with a radius 2.00 m making 7.00 revolutions every 10.0 seconds. What is the magnitude of the acceleration of the ball?
1 : 67.9 m/s2
2 : 38.7 m/s2
3 : 29.3 m/s2
4 : 14.8 m/s2
5 : 74.2 m/s2

A horizontal disk rotates about a vertical axis through its center. Point P is midway between the center and the rim of the disk, and point Q is on the rim. If the disk turns with constant angular velocity, which of the following statements about it are true? (There may be more than one correct choice.)
1 : P and Q have the same linear acceleration.
2 : Q is moving twice as fast as P.
3 : The linear acceleration of Q is twice as great as the linear acceleration of P.
4 : The linear acceleration of P is twice as great as the linear acceleration of Q.
5 : The angular velocity of Q is twice as great as the angular velocity of P.

When a rigid body rotates about a fixed axis, all the points in the body have the same
1 : Tangential speed.
2 : angular acceleration.
3 : tangential acceleration.
4 : linear displacement.
5 : centripetal acceleration.

If an object travels at a constant speed in a circular path, the acceleration of the object is
1 : larger in magnitude the smaller the radius of the circle.
2 : in the same direction as the velocity of the object.
3 : smaller in magnitude the smaller the radius of the circle.
4 : in the opposite direction of the velocity of the object.
5 : zero.

In a shuffleboard game, the puck slides a total of 12 m before coming to rest. If the coefficient of kinetic friction between the puck and the horizontal board is 0.28, what was the initial speed of the puck?
1 : 8.1 m/s
2 : 29.0 m/s
3 : 6.5 m/s
4 : 7.3 m/s

An airplane flies 120 km at a constant altitude in a direction 30.0° north of east. A wind is blowing that results in a net horizontal force on the plane due to the air of 2.40 kN in a direction 10.0° south of west. How much work is done on the plane by the air?
Note on the meaning of 1E8 in answers: 1E8 is an alternative way to write "10 to the power of 8". So 1E8 is 100 000 000. It is a convenient notation when superscripts are difficult to accommodate.
1 : -2.71 × 1E8 J
2 : -0.985 × 1E8 J
3 : -221 × 1E8 J
4 : 221 × 1E8 J
5 : 0.821 × 1E8

A billiard ball traveling at 3.00 m/s collides perfectly elastically with an identical billiard ball initially at rest on the level table. The initially moving billiard ball deflects 30.0° from its original direction. What is the speed of the initially stationary billiard ball after the collision?
Hint: What does "perfectly elastically" imply for the kinetic energy before and after the collision?
1 : 2.00 m/s
2 : 0.866 m/s
3 : 1.50 m/s
4 : 2.59 m/s
5 : 0.750 m/s

Sue and Len throw identical rocks off a tall building at the same time. The ground near the building is flat. Sue throws her rock straight downward. Len throws his rock downward and outward such that the angle between the initial velocity of the rock and the horizon is 30°. Len throws the rock with a speed twice that of Sue's rock. If air resistance is negligible, which rock hits the ground first?
1 : They hit at the same time.
2 : Sue's rock hits first.
3 : Len's rock hits first.
4 : It is impossible to know from the information given

You walk 55 m to the north, then turn 60° to your right and walk another 45 m. How far are you from where you originally started?
1 : 87 m
2 : 50 m
3 : 94 m
4 : 46 m