Question

【題目】一輛質(zhì)量為6t的載貨汽車(chē)，在平直的公路上以90km/h的速度勻速行駛30min，汽車(chē)受到的阻力為車(chē)重的0.06倍(取g=10N/kg)求：

（1）汽車(chē)所受重力和牽引力各是多少?

（2）汽車(chē)有6個(gè)輪子,每個(gè)輪子與地面的接觸面積為 250cm2，汽車(chē)對(duì)地面的壓強(qiáng)是多大？

Answer 1

【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）

牽引力F=Ff=0.06G=0.06×6×104N =3600 N·····················（1分）

⑶壓力F=G==6×104N············································（1分）

壓強(qiáng)p=F/S=6×104N / (250×10-4×6m2)=4×105Pa ················（1分）

【解析】

汽車(chē)行駛的路程s=vt=90km/h

已知汽車(chē)的質(zhì)量m=6t=6000kg，

所以，汽車(chē)所受的重力G=mg=6000kg

因?yàn)槠��?chē)在平直公路上做勻速直線運(yùn)動(dòng)，處于平衡狀態(tài)，受平衡力的作用。汽車(chē)受到的牽引力F=f=0.06G=0.06

汽車(chē)對(duì)地面的壓力F=G=6

汽車(chē)對(duì)地面的壓強(qiáng) P=