Forces acting on block B : A pair of electromagnetic forces between the blocks A and B. A pair of electromagnetic forces between the blocks B and the Earth. A pair of gravitational forces between the blocks B and the Earth. A pair of gravitational forces between the blocks A and B. A pair of action-reaction forces between the man and block A. Weight of the man, block A and block B as action forces on the ground in the downward direction. Reaction of the ground on the man, block A and block B in the upward direction to balance their weights.