Justin moves a desk 3.2 m across a level floor by pushing on it with a constant horizontal force of 250 N. (It slides for a negligibly small distance before coming to a stop when the force is removed.) Then, changing his mind, he moves it back to its starting point, again by pushing with a constant force of 250 N. (a) What is the change in the desk's gravitational potential energy during the round-trip? (b) How much work has Justin done on the desk? Solve in kJ
2006-10-15 11:14:35 · 2 answers · asked by Anonymous in Science & Mathematics ➔ Physics
(a) Gravitational PE=mgh
Since there was no change in height (y) the gravitational potential energy change is zero.
(b) Work = Force * Distance
Work = 250 N * 3.2 m = 800 J
Roundtrip = 2 * 800 J = 1600 J = 1.6 kJ
2006-10-15 11:19:08 · answer #1 · answered by TM 3 · 0⤊ 0⤋
Too much work.
2006-10-15 18:22:08 · answer #2 · answered by Anonymous · 0⤊ 0⤋