問題詳情：
如下圖所示，是一輛汽車透過滑輪組將深井中的物體拉至井口的裝置圖。已知井深12m，物體重
，
汽車重G車=3×104N，汽車勻速拉繩子時的拉力
，汽車受到的阻力爲車重的0.1倍。求：
（1）將物體從井底拉至井口的過程中，汽車拉繩子的拉力對滑輪組做了多少功？
（2）滑輪組的機械效率爲多少？（保留一位小數）
（3）若汽車運動的速度爲3m/s，則將物體由井底拉至井口需要多長時間？
（4）汽車牽引力爲多少？牽引力的功率爲多少？
【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)[來源:學*科*網]
（4）F牽=F′+f=F′+0.1G車=2.2×103N+0.1×3×104N=5.2×103N·························· (1分)
P= F牽υ汽=5.2×103N×3 m/s=1.56×104W (1分)
知識點：力和機械 單元測試
題型：計算題
