Physics help

Question

What coefficient of friction is needed to stop a hockey puck sliding at 12.5 m/s initially over a distance of 60.5 meters?

Answer 1

This problem involves work and kinetic energy. Since the friction opposes the direction of motion, the work is negative:

 

W = ΔKE = - F * Δx

 

Friction F = μ * m * g along a flat surface.

KE = 1/2 m v²

 

You're given the initial velocity, and final velocity is zero (to a stop.)

 

So 0 - 1/2 m (12.5)² = - μ m (9.8m/s²) (60.5m)

 

The masses cancel, and you can solve this, getting μ = 0.132