# physics

posted by stephanie

What is the average useful power output of a person who does 5.50×106 J of useful work in 6.50 h?

235 W correct answer

Working at this rate, how long will it take this person to lift 1850 kg of bricks 1.20 m to a platform? (Work done to lift his body can be omitted because it is not considered useful output here.)

92.6 s correct

can someone give me the steps to achieve these answers?

1. Damon

6.5 h * 3600 s/h = 23400 seconds
so
5.5 * 10^6/2.34*10^4 watts

work done = m g h = 1850*9.81*1.2
power = work/time
235 = work/time
so
time = work/235

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