Question

A 150 kg mass is on a cliff 50 m high. What is its potential energy? 9 How much work is done moving a 2.5 kg book to a shelf 3.0 m high? 10. A 150 pound man runs up a stairway 25 feet above ground level in 10 s. How much work did the man do?

Answer 1

PE=mgh=150kg*9.8m/c² *50m=73500 J

W=F*d=mgd = 2.5*9.8*3.0 = 73.7J

W=mgh=68.0*7.62*9.8 =50.78 J
150 lb = 68.0 kg
25 ft = 7.62m