弹簧秤的示数恒为F0=8N,则弹簧没有伸长,木块A静止不动,并且AB之间的动摩擦力fAB=8N
fAB=μ1mAg
A,B间的摩擦系数μ1 = fAB/(mAg) = 8/(4*10) = 0.2
F-fB-fAB=mBa
fB = F-fAB-mBa = 30-8-5*2 = 12N
fB = μ2(mA+mB)g
B与地面的摩擦系数μ2 = fB / [(mA+mB)g] = 12/[(4+5)*10] = 2/15
弹簧秤的示数恒为F0=8N,则弹簧没有伸长,木块A静止不动,并且AB之间的动摩擦力fAB=8N
fAB=μ1mAg
A,B间的摩擦系数μ1 = fAB/(mAg) = 8/(4*10) = 0.2
F-fB-fAB=mBa
fB = F-fAB-mBa = 30-8-5*2 = 12N
fB = μ2(mA+mB)g
B与地面的摩擦系数μ2 = fB / [(mA+mB)g] = 12/[(4+5)*10] = 2/15