PHYSICS · Multi-part · AP · Physics 1: Algebra-based · Force and Translational Dynamics · Force and Translational Dynamics
Problem
A wooden box of mass 25kg rests on a horizontal floor. The coefficient of static friction between the box and the floor is 0.40, while the coefficient of kinetic friction is 0.30. A person of mass 50kg stands on the box.
(a) Find the minimum horizontal force that must be applied to the box (and person together) so that sliding just begins between the box and the floor.
(b) After motion has begun, the person pulls a horizontal rope attached to the box with a steady force of 80N in the same direction as the external push found in part (a). Determine the additional horizontal force that must now be applied externally to keep the box moving with constant velocity.