— Are you cleaning my room, Serena?
— ______. I can't bear seeing your room in a mess!
A: You are clever
B:Not at all
C:I can't help it
D:No chance
人生的价值就在于发现自己的潜能。( )
如右图所示,斜面长S=10m,高h=4m。用沿斜面方向50N的推力F,在10s内将一个重为100N的物体由斜面底端匀速推到顶端。求:(1)推力的功率;(2)运动过程中物体克服摩擦力所做的功;(3)斜面的机械效率。