1/40,2/40,3/40,4/40,5/40,6/40,7/40,8/40,9/40,10/40,11/40,12/40,13/40,14/40,15/40,16/40,17/40,18/40,19/40,20/40,功,能改变,表示式,重力做功,正功,重力势能降低,W,G,E,p1,E,p2,负功,重力势能增加,弹力做功,正功,弹性势能降低,W,弹,E,p1,E,p2,负功,弹性势能增加,协力做功,正功,动能增加,W,合,E,k2,E,k1,负功,动能降低,其它力做功,正功,机械能增加,W,他,E,2,E,1,负功,机械能降低,21/40,22/40,23/40,24/40,25/40,26/40,27/40,28/40,29/40,30/40,31/40,32/40,33/40,34/40,35/40,36/40,37/40,38/40,39/40,40/40,