Block B, of mass me = 0.5kg, rests on block A, with mass ma = 1.5 kg, which in turn is on a horizontal tabletop
(as shown in fig.). The coefficient of kinetic friction between block A and the tabletop is pk = 0.4 and the
coefficient of static friction between block A and block B is u = 0.6. A light string attached to block A passes over
a frictionless, massless pulley and block C is suspended from the other end of the string. What is the largest mass
mc (in kg) that block C can have so that blocks A and B still slide together when the system is released from rest?
Answers
Answer:
2.3 kg
Explanation:
Mass of block A = 1.5 kg
Mass of block B = 0.5 kg
The Coefficient of kinetic friction between block A and the tabletop = 0.4
The Coefficient of static friction between block A and block B 0.6
In this problem, the weight of block C will pull block A to right with force equal to the weight of block C.
The kinetic friction between block A and tabletop due to the mass of A & B will try to resist the pull due to the C.
Since the condition is that block B needs to slide together with A, the only force acting on B will be due to the static friction which will be static friction multiplied by the weight of B acting on B in the right direction. The opposite of this friction will be acting on block A in the left direction opposing the pull of C.
