Forces and Electricity

A motorboat, which has a speed of 5.0 meters per second in still water, is headed east as it crosses a river flowing south at 3.3 meters per second. What is the magnitude of the boat’s resultant velocity with respect to the starting point?

• 3.3 m/s
• 5.0 m/s
• 6.0 m/s
• 8.3 m/s

A car traveling on a straight road at 15.0 meters per second accelerates uniformly to a speed of 21.0 meters per second in 12.0 seconds. The total distance traveled by the car in this 12.0-second time interval is

• 36.0 m
• 180. m
• 216 m
• 252 m

A 0.149-kilogram baseball, initially moving at 15 meters per second, is brought to rest in 0.040 second by a baseball glove on a catcher’s hand. The magnitude of the average force exerted on the ball by the glove is

• 2.2 N
• 2.9 N
• 17 N
•  56 N

Which body is in equilibrium?

•  a satellite moving around Earth in a circular orbit
• a cart rolling down a frictionless incline
•  an apple falling freely toward the surface of Earth
• a block sliding at constant velocity across a tabletop

How much time is required for the stone to reach the level ground below? [Neglect friction.]

• 3.19 s
• 5.10 s
• 10.2 s
• 12.5 s

On the surface of Earth, a spacecraft has a mass of 2.00 × 10⁴ kilograms. What is the mass of the spacecraft at a distance of one Earth radius above Earth’s surface? 

•  5.00 × 10³ kg
•  2.00 × 10⁴ kg
• 4.90 × 10⁴ kg
•  1.96 × 10⁵ kg

A student pulls a 60.-newton sled with a force having a magnitude of 20. newtons. What is the magnitude of the force that the sled exerts on the student?

• 20 N
• 40 N
• 60 N
• 80 N

Which object has the greatest inertia?

• A
• B
• C
• D

 A ball is thrown vertically upward with an initial velocity of 29.4 meters per second. What is the maximum height reached by the ball? [Neglect friction.]

• 14.7 m
• 29.4 m
• 44.1 m
• 88.1 m

At the instant shown, the centripetal force acting on mass m is directed toward point

• A
• B
• C
• D