题目内容
【题目】一辆质量为6t的载货汽车,在平直的公路上以90km/h的速度匀速行驶30min,汽车受到的阻力为车重的0.06倍(取g=10N/kg)求:
(1)汽车所受重力和牵引力各是多少?
(2)汽车有6个轮子,每个轮子与地面的接触面积为 250cm2,汽车对地面的压强是多大?
【答案】⑴s=vt························································(1分)
=90km/h × 30/60 h =45km··································(1分)
⑵重力G=mg=6×103kg×10N/kg=6×104N ························(1分)
牵引力F=Ff=0.06G=0.06×6×104N =3600 N·····················(1分)
⑶压力F=G==6×104N············································(1分)
压强p=F/S=6×104N / (250×10-4×6m2)=4×105Pa ················(1分)
【解析】
汽车行驶的路程s=vt=90km/h
已知汽车的质量m=6t=6000kg,
所以,汽车所受的重力G=mg=6000kg
因为汽车在平直公路上做匀速直线运动,处于平衡状态,受平衡力的作用。汽车受到的牵引力F=f=0.06G=0.06
汽车对地面的压力F=G=6
汽车对地面的压强 P=
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