如下图所示,是一辆汽车通过滑轮组将深井中的物体拉至井口的装置图。已知井深12m,物体重,汽车重G车=3×104...
问题详情:
如下图所示,是一辆汽车通过滑轮组将深井中的物体拉至井口的装置图。已知井深12m,物体重,汽车重G车=3×104N,汽车匀速拉绳子时的拉力,汽车受到的阻力为车重的0.1倍。求:
(1)将物体从井底拉至井口的过程中,汽车拉绳子的拉力对滑轮组做了多少功?
(2)滑轮组的机械效率为多少?(保留一位小数)
(3)若汽车运动的速度为3m/s,则将物体由井底拉至井口需要多长时间?
(4)汽车牵引力为多少?牵引力的功率为多少?
【回答】
(1)n=3 s=3h=3×12m=36m······································································ (1分)
W=Fs=2.2×103N×36m=7.92×104J·························································· (1分)
(2)η==······················ (2分)
(3)υ物=1/3υ=1/3×3m/s=1m/s···································································· (1分)
t物=h/υ物=12m/1 m/s=12s································································ (1分)[来源:学*科*网]
(4)F牵=F′+f=F′+0.1G车=2.2×103N+0.1×3×104N=5.2×103N·························· (1分)
P= F牵υ汽=5.2×103N×3 m/s=1.56×104W (1分)
知识点:力和机械 单元测试
题型:计算题