Science · Grades 8–11
Power
One watt is one joule per second.
The key idea
One watt is one joule per second.
P_avg = energy transferred / time
Worked examples
A device transfers 192 J in 12 s. Find average power in W.
192 ÷ 12 = 16
16 W
A device transfers 495 J in 5 s. Find average power in W.
495 ÷ 5 = 99
99 W
Try it yourself
A device transfers 3393 J in 39 s. Find average power in W.
A device transfers 392 J in 28 s. Find average power in W.
Check your understanding
Answers and marking notes
- 87 W
3393 ÷ 39 = 87
- 14 W
392 ÷ 28 = 14
Further reading and review references
These are reference links, not copied exercises, institutional endorsement or proof of independent review.
Learning preview · teacher review required. Grade bands are approximate, not official curriculum alignment.