Power
3 marks · NormalA table shows the time taken for four students to lift identical boxes through the same vertical distance:
| Student | Time taken (s) |
|---|---|
| Ali | 10 |
| Ben | 8 |
| Chloe | 12 |
| Dina | 6 |
Each box requires 300 J of work to be lifted.
Which student had the greatest power output?
Calculate the power output for this student.
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) Dina
(b) 50 W
Common mistakes: Picking student with least power by mistake; Not using correct formula
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · Identifies Dina as the student with the greatest power (shortest time)
M1 (b) · 1 mark · Uses P = W / t with Dina's time (6 s) (follow-through)
A1 (b) · 1 mark · Correct final answer with unit (50 W, or correct follow-through) (follow-through)
Worked solution
a) Dina took the least time, so had the highest power output.
b) Power = work / time = 300 J / 6 s = 50 W.