what is the PE of a 10 kg box that drops 10 meters?

Change of PE over a height of 10m = M G H = (10) (9.8) (10) = 980 joules.When the box hits the bottom, it has 980 joules less PE than it hadbefore it started dropping.  (As well as 980 joules more kinetic energy.)

P.E = mgh                            M= MASSG= ACCELERATION DUE TO GRAVITYH = HEIGHTP.E= 10 * 10 * 10P.E = 1000J