# A sled traveling at a speed of #3.0# #ms^-1# slows to a stop #4.0# #m# from the point where its passenger rolled off. What is the magnitude of the horizontal net force that slows the #110# #N# sled?

##### 1 Answer

First step is to find the acceleration (deceleration) of the sled, which turns out to be

Then we can use Newton's Second Law to find

#### Explanation:

To find the acceleration of the sled, we use:

Rearranging:

The minus sign just means the acceleration is in the opposite direction to the velocity: the sled is slowing down.

We want to use Newton's Second Law to find the force:

We're not given the mass of the sled, but we are told its weight is

So:

Again, the minus sign just means the force is acting in the opposite direction to the sled's initial motion.