At the gym, a man pulls a bar on a machine that works the muscles of the upper back. It takes him 0.5 seconds to raise 30 kilograms of weights a vertical distance of 0.5 meters. Which of these exerts the same power output? (Estimate g as 10 m/s2.)
A) lifting 25 kilograms a distance of 2.4 meters in 2.0 seconds
B) lifting 45 kilograms a distance of 2.4 meters in 3.0 seconds
C) leg pressing 45 kilograms a distance of 0.5 meters in 0.5 seconds
D) bench pressing 30 kilograms a distance of 0.5 meter in 1.5 seconds