如图所示,质量为2.5t的汽车在平直的公路上匀速行驶,在其前方有一固定的测速仪向汽车发出两次短促的超声波信号,第一次发出信号到接收到信号用时0.6s,第二次发出信号到接收到信号用时0.45,测出汽车的速度为34m/s。已知汽车在公路上匀速行驶时受到的阻力是车重的0.02倍,超声波的速度为340m/s。(g取10N/kg)求: (1) 汽车匀速行驶时受到的牵引力; (2) 汽车匀速行驶10s内牵引力做的功; (3) 测速仪两次发出信号的时间间隔He makes people
pleased with _______ by making them first pleased with _______.
A. them, himself B.
himself, them
C. him, them D.
him, themselves