Question

Figure shows a block of mass m resting on a plank of mass M, placed on a smooth horizontal surface The coefficient of friction between the block and plank is u. A horizontal force F is applied on the plank which varies with time t as F = kt (k is a positive constant). Select the correct alternative.

1) After time t = ug(M + m)/k, relative motion between block and plank starts

(2) Friction force between the block and plank remains constant after t = ug(M + m)/k
till the contact between two is lost
(3) Contact force between plank and ground increases with time

(4) Block will never move relative to the plank​​

Answer 1

Answer:

2will be the correct information