Energy Resources and Energy Transfers
4 marks · EasyA ball of mass 0.6 kg is lifted from the floor onto a table 0.8 m high. It is then pushed and rolls off the edge, falling to the ground below.
Calculate the increase in gravitational potential energy (GPE) of the ball when it is placed on the table. Take gravitational field strength as 10 N/kg.
State what happens to the GPE of the ball as it falls to the ground.
Name one other store of energy that the ball has just before it touches the ground.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
(a) 4.8 J
(b) The GPE is transferred (converted) into kinetic energy as the ball falls.
(c) kinetic energy
Common mistakes: wrong formula for GPE; incorrect units
Show mark scheme and worked solution
Marking points
M1 (a) · 1 mark · Uses GPE= m × g × h correctly. (follow-through)
A1 (a) · 1 mark · Correct final value with unit (4.8 J).
B1 (b) · 1 mark · States GPE is transferred to kinetic energy as the ball falls.
B1 (c) · 1 mark · States kinetic energy as the other store just before hitting the ground.
Worked solution
a) GPE = mass × gravity × height = 0.6 kg × 10 N/kg × 0.8 m = 4.8 J
b) The GPE is converted into kinetic energy as the ball falls.
c) Just before impact, the ball has kinetic energy.