1）由mgR=0.5mv^2-0
N-mg=mv^2/R N=3mg=30N N'=-N
压力大小30N 方向竖直向下
（2）h=0
由mgR-μmgx1=0 10R-5μ=0
h=0.5
mg(R+h)-μmgx2=0 10R+5-15μ=0
μ=0.5 R=0.25m
(3)由mg(R+h)=0.5mv0^2
由动量守恒
mv0=(M+m)v
由能量守恒
0.5mv0^2=0.5(M+m)v^2+μmgx
x=5(0.25+h)/3
Q=μmgx=25(0.25+h)/3J
1）由mgR=0.5mv^2-0
N-mg=mv^2/R N=3mg=30N N'=-N
压力大小30N 方向竖直向下
（2）h=0
由mgR-μmgx1=0 10R-5μ=0
h=0.5
mg(R+h)-μmgx2=0 10R+5-15μ=0
μ=0.5 R=0.25m
(3)由mg(R+h)=0.5mv0^2
由动量守恒
mv0=(M+m)v
由能量守恒
0.5mv0^2=0.5(M+m)v^2+μmgx
x=5(0.25+h)/3
Q=μmgx=25(0.25+h)/3J