Energy Practice Problems
18. Susan stands at the edge of the diving board 3.o meters above the surface of the water (height of zero). If she has a mass of 65 kg,
a) What is her PE standing on the board?
b) Susan has no speed in her standing position on the board, so what is her KE?
c) What is Susan’s total (mechanical) energy while she was on the board?
d) What was Susan’s PE just before she hit the water? (hint: height = 0)What is Susan’s KE just before she hits the water if she is in vacuumland? (Remember, conservation of energy)
e) What is Susan’s KE just before she hits the water if she looses 200J of heat to air resistance? (Remember, conservation of energy)
f) How fast of Susan going just before she hit the water in vacuumland?
19. A baby carriage is sitting at the top of a hill that is 21 m high. The carriage with the
baby weighs 24 lbs. (1kg = 2.2lbs) The carriage has _________________ energy. Calculate it.
20. A ski jumper is leaving the ramp (h=0.00) at a velocity of 24.5m/s. This jumper has a mass of 125kg (including skis, gear, etc).
A) What is the jumpers KE at the time that he leaves the ramp?
B) What is his GPE at that time?
C) At the top of his jump, how fast is he going?
D) What is his KE at the top of his jump?
E) What is his PE at the top of his jump?
F) How high does he go?
21) A skateboarder (m=55kg) is at the top of a half pipe, not moving, preparing to skate down. If the top of the half pipe is 15m and the bottom is 2.5m off of the ground, how fast will be be going when he hits the bottom of the half pipe? (Hint, TE1=TE2)
22. The baby carriage from above begins rolling down the hill. The bottom of the hill has a height of zero (thus no potential energy). If the stroller loses 50J of energy in heat and 75J of energy to sound as it rolls down, how fast will it be going at the bottom of the hill. (Hint, use TE1=TE2)
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