A 4 kg block A is placed on the top of a block B of mass 8 kg , which rests on a smooth table. A just slips on B when a force of 12 N is applied on A . Then, the maximum horizontal force required to make both A and B move together is :

Step-by-step solution

The mass of block A=4 ~kg Force of friction between A and B=12 ~N Mass of block A and B=4+8=12 ~kg i e , mass is increased 3 times. The force of friction also increases 3 times =12 3=36 N Hence, maximum horizontal force required =36 ~N