Question

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

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

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