如图所示,一金属箱固定在倾角为
![](http://math.21cnjy.com/mml2svg?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmsup%3E%3Cmrow%3E%3Cmn%3E37%3C%2Fmn%3E%3C%2Fmrow%3E%3Cmo%3E%C2%B0%3C%2Fmo%3E%3C%2Fmsup%3E%3C%2Fmrow%3E%3C%2Fmath%3E)
的足够长固定斜面上,金属箱底面厚度不计,箱长l
1=4.5m,质量m
1=8kg。金属箱上端侧壁A打开,距斜面顶端l
2=5m。现将质量m
2=1kg的物块(可视为质点)由斜面顶端自由释放,沿斜面进入金属箱,物块进入金属箱时没有能量损失,最后与金属箱下端侧壁B发生弹性碰撞。碰撞的同时上端侧壁A下落锁定并释放金属箱。已知物块与斜面间的动摩擦因数μ
1=0.3,与金属箱内表面间的动摩擦因数μ
2=0.125,金属箱与斜面间的动摩擦因数μ
3=
![](http://math.21cnjy.com/mml2svg?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmfrac%3E%3Cmrow%3E%3Cmn%3E0.625%3C%2Fmn%3E%3C%2Fmrow%3E%3Cmn%3E3%3C%2Fmn%3E%3C%2Fmfrac%3E%3C%2Fmrow%3E%3C%2Fmath%3E)
,重力加速度g取10m/s
2 , sin
![](http://math.21cnjy.com/mml2svg?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmsup%3E%3Cmrow%3E%3Cmn%3E37%3C%2Fmn%3E%3C%2Fmrow%3E%3Cmo%3E%C2%B0%3C%2Fmo%3E%3C%2Fmsup%3E%3C%2Fmrow%3E%3C%2Fmath%3E)
=0.6,cos
![](http://math.21cnjy.com/mml2svg?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmsup%3E%3Cmrow%3E%3Cmn%3E37%3C%2Fmn%3E%3C%2Fmrow%3E%3Cmo%3E%C2%B0%3C%2Fmo%3E%3C%2Fmsup%3E%3C%2Fmrow%3E%3C%2Fmath%3E)
=0.8,求: