Question

A body builder loads a bar with 550 newtons (~125 pounds) of weight and pushes the bar over her head 10 times. Each time she lifts the weight 0.5 meters. How much work did she do? 275 Joules. If she lifts the bar 10 times in 20 seconds, how much power did she use?

Answer 1

Work = (force) x (distance)

 (550 newtons) x (0.5 meter) = 275 joules each lift .

 (275 joules/lift) x (10 lifts)  =  2,750 joules of work all together.


Power = (work done) / (time to do the work)

           = (2,750 joules) / (20 seconds)

           =    137.5 watts .        (about 0.18 horsepower)