x方向 F cOs a-Fn-F y方向Fsia+FN,-P4=0 F=uF B(x方向F-FB=m y方向FN=B F B 解得: B [cos a +usin a F-u(m +mB)gl mt+m B F=m2(a+1g)=m2 coS at usn a F 1+m A B( )F (m m )g m m a A B A B + − + + = cos   sin   1( ) F m m F m a g m A B T B B ++ = + =     cos sin A NA F = F F sin + FN − PA = 0 A  F cos  − FT − FA = m A a m A x方向 y方向 解得： A F FT NA F FA B PA FT NB F FB PB mB FT − FB = mBa FNB = PB x方向 y方向 NB NB F = F