Question

A crate of oranges on a horizontal floor has a mass of 25.0 kg. The coefficient of static friction is 0.62. The coefficient of kinetic friction is 0.52. The worker pulls the crate with a force of 160 N. A) Does the crate move? B) How do you know if the crate is moving or not? Explain it by comparing the magnitude of the friction with the magnitude of the applied force. C) What is the equation to calculate the kinetic friction? D) What is the kinetic friction on the crate?

Answer 1

The crate will not move because the applied force of 160 N is less than the maximum static friction of 151.9 N. The kinetic friction on the crate, once moving, would be 127.4 N.

Step-by-step explanation:

To determine whether the crate moves, we compare the force applied to the crate with the maximum static friction force. The maximum static friction force (ℓs(max)) is given by fs(max) = μsN, where μs is the coefficient of static friction, and N is the normal force. The normal force is equal to the weight of the crate, which is the mass (m) times the acceleration due to gravity (g), so N = mg. For a 25.0 kg crate, N = (25.0 kg)(9.8 m/s²) = 245 N. With μs = 0.62, the maximum static friction is fs(max) = (0.62)(245 N) = 151.9 N.

A) The crate will not move because the applied force (160 N) is less than the maximum static friction.

B) You know the crate is not moving because the magnitude of static friction is greater than the applied force.