Answer:

Step-by-step explanation:
The frictional force is given by:

According to Newton's second law:

Replacing (2) and (3) in (1):

To find the mass of the girl on the sled, we divide their weigh into the acceleration of gravity:

Replacing (5) in (4). Solving for a:

Finally, using this kinematic equation, we calculate the distance traveled before coming to a rest (
):
