(1)整體分析,摩擦力為內(nèi)力抵消,所以動量守恒
mV0=(m+M)v
v=mV0/(M+m)
(2)動量定理
因為一直是受恒定摩擦力umg
ft=mΔv
umg*t=m*(v0-v)
t=MV0/[ug(M+m)]
(3)熱量=能量損失
=(1/2)mV0^2-(1/2)mv^2-(1/2)Mv^2
=(1/2)mV0^2-(1/2)(M+m)[mV0/(M+m)]^2
=(1/2)MmV0^2/(M+m)
小車滑行距離,小車一直加速,加速度為a=umg/M
時間為t=MV0/[ug(M+m)]
s=(1/2)at^2=(1/2)umg/M[MV0/[ug(M+m)]]^2
=(1/2)MmV0^2/[ug(M+m)^2]