A crate is at rest on a rough horizontal loading dock
PHYSICS · Multi-part · CBSE · Physics · Laws of Motion · Laws of Motion
Problem
A 25kg crate is at rest on a rough horizontal loading dock. The coefficient of static friction between the crate and the dock is 0.40, and the coefficient of kinetic friction is 0.30. A warehouse worker plans to push on the crate with a force that is directed horizontally.
Answer the following, showing all reasoning and including proper units.
(a) Draw a clearly labeled free-body diagram for the crate while the worker is pushing but the crate has not yet begun to slide.
(b) Determine the minimum magnitude of the horizontal force the worker must exert to start the crate moving.
(c) If the worker continues to push with the same force found in part (b) after the crate begins to slide, calculate the magnitude and direction of the crate’s initial acceleration.
(d) Describe qualitatively how the kinetic friction acting on the crate would change, if at all, as the crate gains speed, and explain your reasoning.