Question

A girl is sitting in a sled sliding horizontally along some snow (there is friction present).

The normal force supporting the girl and sled is 636 N.

If the coefficient of static friction is 0.38, and the coefficient of kinetic friction between snow and sled is 0.25, what is the force of friction exerted on the sled?

Answer 1

Answer:

159 N

Explanation:

The force of friction is a resistive force that acts against an object in motion (or on the verge of moving).

There are two types of force of friction:

• Force of static friction: it occurs when the object is still at rest
• Force of kinetic friction: it occurs when the object is sliding on a surface and it is in motion

In this problem, we are in the 2nd situation, so we want to calculate the force of kinetic friction.

This force is given by:

$F=\mu_k N$

where

$\mu_k$ is the coefficient of kinetic friction

N is the normal force exerted on the object

For the sled and the girl in this problem,

$\mu_K = 0.25$ is the coefficient of kinetic friction

N = 636 N is the normal force

So the force of friction is

$F=(0.25)(636)=159 N$