# Mechanics

1. What is the tangential speed of Nairobi, Kenya, a city near the equator? The earth makes one revolution every 23.93 h and has an equatorial radius of 6380 km.

A) 74.0 m/s

B) 116 m/s

C) 148 m/s

D) 232 m/s

E) 465 m/s

2. The radius of the earth is 6.38 x 106 m and its mass is 5.98 x 1024 kg. What is the acceleration due to gravity at a height of 1.28 x 107 m above the earth's surface?

A) 1.08 m/s2

B) 2.15 m/s2

C) 9.80 m/s2

D) 0.659 m/s2

E) 0.114 m/s2

3. During hockey practice, two pucks are sliding across the ice in the same direction. At one instant, a 0.18-kg puck is moving at 16 m/s while the other puck has a mass of 0.14 kg and a speed of 3.8 m/s. what is the velocity of the center of mass of the two pucks?

A) 5.0 m/s

B) 7.0 m/s

C) 9.0 m/s

D) 11 m/s

E) 13 m/s

4. A wheel with a 0.10 m radius is rotating at 35 rev/s. It then slows uniformly to 15 rev/s over a 3.0-s interval. What is the angular acceleration of a point on the wheel?

A) -2.0 rev/s2

B) 0.67 rev/s2

C) -6.7 rev/s2

D) 42 rev/s2

E) -17 rev/s2

5. A train travels due south at 60 m/s. It reverses its direction and travels due north at 60 m/s. What is the change in velocity of the train?

A) 120 m/s, due north

B) 120 m/s, due south

C) 60 m/s, due north

D) 60 m/s, due south

E) zero m/s

6. An artificial satellite in a circular orbit around the Sun has a period of 8 years. Determine the ratio of the satellite's orbital radius about the Sun to the earth's orbital radius about the Sun. Assume that the earth's orbit about the Sun is circular.

A) 1

B) 2

C) 4

D) 8

E) 23

7. An arrow is shot horizontally from a height of 4.9 m above the ground. The initial speed of the arrow is 45 m/s. Neglecting friction, how long will it take the arrow to hit the ground?

A) 9.2 s

B) 6.0 s

C) 1.0 s

D) 1.4 s

E) 4.6 s

#### Solution Summary

Reasoned answers provided.