a small child is sliding down a 25 degree slide at a uniform velocity of 1.0 m/s. If the child weighs 210 N, find the coefficient of friction between the slide and the child.

Answer 1

Resolve forces along and perpendicular to the inclined plane:

Along the plane,
mg sinθ - μN = 0
N is the normal force equal to mgcosθ
Substituting,
mgsinθ-μmgcosθ=0
Solve for μ to get:
μ=tan(θ)
Note that μ is not dependent on the mass of the moving object, nor the magnitude of the uniform velocity.