Answer:
159 N
Explanation:
There are two types of force of friction:
- Static friction: this is the force of friction that occurs when the object is at rest
- Kinetic friction: this is the force of friction that occurs when the object is in motion
In this problem, the girl is sitting on the sled, and the sled is sliding: this means that the object is in motion, therefore the force of friction that we have to calculate in this problem is the force of kinetic friction.
The force of kinetic friction acting on an object sliding over a flat surface is given by
where
is the coefficient of kinetic friction
N is the normal force on the object
In this problem:
N = 636 N
Therefore, the force of kinetic friction is