Energy Resources and Energy Transfers
4 marks · EasyA student pushes a box with a constant force of 30 N so that it moves 4 m across the floor.
Name the unit of work done in this situation.
Calculate the work done by the student on the box. Show your working.
State the principle of conservation of energy as it applies to this situation.
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) joule (J)
(b) 120 J
(c) Energy is not created or destroyed; it is transferred from one store to another.
Common mistakes: Missing unit for work done; Not linking work done to energy transferred
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · States correct unit (Joule or J).
M1 (b) · 1 mark · Substitutes correctly: work = force × distance.
A1 (b) · 1 mark · Correct value: 30 N × 4 m = 120 J.
B1 (c) · 1 mark · Correctly states the principle of conservation of energy.
Worked solution
a) The unit of work done is the joule (J).
c) The principle of conservation of energy states that energy is not created or destroyed, only transferred from one store to another.