Aman of 75 kg is pushing a heavy box along flat floor. the coefficient of sliding friction between the floor and the box is 0.20, and the coefficient of static friction between the man's shoes and the floor is 0.80.
(a) if the man pushes downward on the box at an angle of 30 degrees, what is the maximum mass of the box he can move?
(b)if the man pushes upward on the box at an angle of 30 degrees, what is the maximum mass of the box he can move?
don't copy a previous answer the one i found was incorrect i believe.