work power and forces

Question

You push shoes against the turf to cause a normal contact force of 600N. A machine then pulls the turf surface until it slides under the shoe. The machine pulls with a force of 400N before the turf surfaces begin to slide. What is the coefficient of static friction between the soccer cleat and the turf?

Answer 1

The force of friction is give by F_friction = μ x N where μ is the coefficient of friction and N is the normal force.

In this case, the normal force is given as 600N and the friction force as 400 N. Solving for μ, we get μ

μ = 400 N / 600 N = 0.67.

Remember that the static frictional force is the force needed tangentially to start a mass moving in the presence of friction between the surface and the object.