一辆重型卡车匀速行驶时发动机的功率为202kW,速度为80km/h,汽车行驶2h,发动机做的功是多少?卡车的牵引是多大?

(1) W = P * t ;
=> W = 202kw * 2h = 202000*7200 J = 1.4544 * 10^9 ;
(2) P = W / t ;
=> P = (F*S) / t = F*(S / t ) = F * v ;
=> F = P / v = 202kw / 80km/h = 202000w / (80 / 3.6)m/s = 9090 N .谢谢。