Laws of Motion on a snow sled

[hatcheezy]

Homework Statement

A person on a snow sled(total mass of 60.0kg) starts from rest at a vertical height of 24.0m above the bottem of the hill. If aconstant frictional force of 70.0 N opposes their motion as they slide down the hill and the length of the slope is 65.0m, whta is their speedat the bottem of teh hill?

Homework Equations

PE = KE + W
mgh = 1/2mv² + 1/2kx²

The Attempt at a Solution

(60kg)(9.8m/s²)(24m) = 1/2(60kg)v² + 1/2(70N)(65m)²

14112 = 30v² +147875

v=66.77m/s ??

 

[Jack21222]

1/2kx^2? That's the equation for a spring, not for the energy lost due to friction.

Just check your dimensional analysis, your units don't make sense.

 

[RoryP]

Recall the equation for Work Done...