Question

起重机把质量为0.5t的钢材,以1.5m/s的速度匀速向上提升,求;(g取10n/kg)

Answer 1

1 .1min内起重机将重物提升的高度是多少?

H = vt = 1.5 * 60 =90m

2 .1min内起重机做了多少有用功?

W = mgH = 500 * 10 * 90 = 450000 J

3 .若起重机的效率为60%,它的总功率多大?

Wo = W/0.6 =75000J

P = Wo/t = 1250 W