Question

如下圖所示，是一輛汽車通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(shí)的拉力，汽車受到的阻力為車重的0.1倍。求：

（1）將物體從井底拉至井口的過程中，汽車?yán)�繩子的拉力對(duì)滑輪組做了多少功？

（2）滑輪組的機(jī)械效率為多少？（保留一位小數(shù)）

（3）若汽車運(yùn)動(dòng)的速度為3m/s，則將物體由井底拉至井口需要多長時(shí)間？

（4）汽車牽引力為多少？牽引力的功率為多少？

Answer 1

（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(xué)*科*網(wǎng)]

　�。�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)