A machine does 24 J of work in 3 s. What is its power?

A machine does 24 J of work in 3 s. What is its power?

• A. 6 W
• B. 10 W
• C. 12 W
• D. 8 W

Answer: (D)

Power is the rate at which work is done or energy is transferred. It is found from P = W/t, where W is work and t is time. The machine does 24 joules of work in 3 seconds, so P = 24 J ÷ 3 s = 8 J/s, or 8 watts. This means energy is being transferred at 8 joules every second. If the same amount of work happened faster, the power would be higher; if it took longer, the power would be lower. For context, 6 watts would require 18 J in 3 s, 10 watts would require 30 J, and 12 watts would require 36 J in 3 s, which don’t match the given work. The rate here is 8 watts.

Power is the rate at which work is done or energy is transferred. It is found from P = W/t, where W is work and t is time. The machine does 24 joules of work in 3 seconds, so P = 24 J ÷ 3 s = 8 J/s, or 8 watts. This means energy is being transferred at 8 joules every second. If the same amount of work happened faster, the power would be higher; if it took longer, the power would be lower. For context, 6 watts would require 18 J in 3 s, 10 watts would require 30 J, and 12 watts would require 36 J in 3 s, which don’t match the given work. The rate here is 8 watts.