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A 490 kg dragster accelerates from rest to a final speed of 104 m/s in 400 m (about a quarter of a mile) and encounters an average frictional force of 1200 N. What is its average power output in watts and horsepower if this takes 7.3 s? W hp
(a) What is the average useful power output (in W) of a person who does 5.1×106 J of useful work in 8.5 h? W (b) Working at this rate, how long (in s) will it take this person to lift 2200 kg of bricks 1.3 m to a platform? (Work done to lift his body can be omitted because it is not considered useful output here.) S