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Laws of Motion on a snow sled

  • Thread starter hatcheezy
  • Start date
  • #1
8
0

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 ??
 

Answers and Replies

  • #2
172
1
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.
 
  • #3
76
0
Recall the equation for Work Done...
 

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