(1)(2分)減小壓強(qiáng) 增大摩擦
(2)(3分)推土機(jī)做功W = Pt = Fs
F=Pt/s=2.0*10^5w*60s/12m=1.0*10^5N
由于推土機(jī)勻速運(yùn)動(dòng),則推土機(jī)受到的阻力Ff =1.0 x 105N
(1)(2分)減小壓強(qiáng) 增大摩擦
(2)(3分)推土機(jī)做功W = Pt = Fs
F=Pt/s=2.0*10^5w*60s/12m=1.0*10^5N
由于推土機(jī)勻速運(yùn)動(dòng),則推土機(jī)受到的阻力Ff =1.0 x 105N