A box is being lowered down a wall at constant speed by a girl, as shown. Her hand is pushing on the edge of the box with 50 N of force at a 45◦ angle with respect to the horizontal. The box weighs 40 N. Find the coefficient of kinetic friction between the box and the wall.
b) Now imagine the box is stationary. The coefficient of static friction between the box and wall is 0.60. The girl still pushes at a 45◦ angle. Over what range of force (Fmin,Fmax) can the girl push the box without causing it to move?