Questions: Power: How Fast Work Gets Done
3 questions to test your understanding
Score: 0 / 3
Question 1 Multiple Choice
A crane lifts a load, doing 6,000 J of work in 30 seconds. What is the crane's power output?
A180,000 W
B200 W
C6,030 W
D5,970 W
Power = Work / Time = 6,000 J / 30 s = 200 W.
Question 2 True / False
If two motors do the same amount of work but one takes half the time, the faster motor has twice the power.
Answer: True
P = W/t. Same work in half the time means double the power.
Question 3 Short Answer
A 60 W light bulb is left on for 5 seconds. How much energy does it use?
Think about your answer, then reveal below.
Model answer: 300 J, because Energy = Power × Time = 60 × 5 = 300 J.
Rearranging P = W/t gives W = P × t. 60 watts × 5 seconds = 300 joules.