A man standing inside an elevator, which is moves with a constant acceleration, it holds a 3-kg block B between two other blocks in such a way that the movement of B in relation to A and C is imminent. If it is known that the coefficients of friction between all surfaces son μ s=0.30 and μk=0.25, determine (a) the acceleration of the elevator if it is moving upward and each of the forces exerted by the man on blocks A and C has a horizontal component equal to twice the weight of B, b) the horizontal components of the forces exerted by man on blocks A and C if the elevator acceleration is 2.0 m / s^2 downwards.

A man standing inside an elevator, which is moves with a constant acceleration, it holds a 3-kg block B between two other blocks in such a way that the movement of B in relation to A and C is imminent. If it is known that the coefficients of friction between all surfaces son μ s=0.30 and μk=0.25, determine (a) the acceleration of the elevator if it is moving upward and each of the forces exerted by the man on blocks A and C has a horizontal component equal to twice the weight of B, b) the horizontal components of the forces exerted by man on blocks A and C if the elevator acceleration is 2.0 m / s^2 downwards.