(1) f = (g+g shift) /3
get:g move = 3f-g = 3×400n- 1000n = 200n。
(2) It is useful to overcome things and redo them;
W you = GH =1000 n×1m =1000 j.
(3) p = w total /t = fs/t, s = 3h = 3m.
= 400 Newton× 3m/20s
=60W
24、
(1) According to the lever balance condition: g× 0.9 = f× 1.5.
Solution: f = 500 n× 0.9 m/1.5 m = 300 n.
(2) Work done: w = fs = 300n× 0.4m = 120J.
W total = 120J× 30 = 3600J.
Power: p = w total /t = 3600J/60s = 60W