AP Physics CH 10

A 2.0 kg book is lying on a 0.75-m-high table. you pick it up and place it on a bookshelf 2.3 m above the floor.
during this process 
A. how much work does gravity do on the book?
B. how much work does your hand do on the book?

• A. -30 J
  B. 30 J
• A. -40 J 
  B. 40 N
• A. -100 J
  B. -50 J
• A. 0.29 J
  B. 4.98 J

A boy flies a kite with the string at a 30 angle to the horizontal. The Tension in the string is 4.5 N. How much work does the string do on the boy if the boy. 
A. stands still?
B. walks a horizontal distance of 11 m away from the kite? 
C. Walks a horizontal distance of 11 m toward the kite? 

• A. 6.8 X 10^4 J
  B. 30 J
  C. 17 m/s
• A. 10 J
  B. 50 J
  C. -50 J
• A. 0 J  
  B. -43 J
  C. 43 J 
• A. 0.1 J 
  B. 43 J
  C. -43 J 

A roller coaster starts from rest at its highest point and then descends on its (friction-less) Track. Its speed is 30 m/s when it reaches ground level. what was its speed when its height was half that of its starting point?

• 30 m/s
• 15 m/s
• 10 m/s 
• 21 m/s

A worker uses a pulley and a rope to raise a 20 kg weight to a height of 2 m. If it takes 4 s to do this, about how much power is the worker supplying?

• 100 N
• 100 W
• 50 W
• 110 W

A block slides down a smooth ramp, starting from rest at a height h. When it reaches the bottom it's moving at speed v. It then continues to slide up a second ramp. At what height is its speed equal to v/2 ? 

• 2h
• h/4
• 3h/4
• h/2

A 20 g plastic ball is moving to the left at 30 m/s. how much work must be done on the ball to cause it to move to the right at 30 m/s? 

• 0.0 J
• 60 J
• 25 J
• 39 J

a 50 g marble moving at 2.0 m/s strikes a 20 g marble at rest. what is the speed of each marble immediately after that collision? assume the collision is perfectly elastic and the marbles collide head-on 

• 0.86 m/s and 2.9 m/s
• 1 m/s and 3 m/s
• .5 m/s and .24 m/s
• 2 m/s and 3 m/s 

a 550 g elevator accelerates upward at 1.2 m/s^2 for the first 15 m of its motion. how much work is done during this part of its motion by the cable that lifts the elevator. 

• 100 kJ
• 91 kJ
• 9.1 kJ
• 91 J

a 1000 kg sports car accelerates from 0 to 30 m/s in 10 s. what is the average power of the engine 

• 50 kW
• 40 W
• 45 kW
• 44.5 kW

An elevator weighing 2500 N ascends at a constant speed of 8.o m/s. how much power must the motor supply to do this?

• 2.0 X 10^4 W
• 4 X 10^5 W
• 2.1 X 10^4 W
• 2.0 X 10^8 W