Conservation of energy of a toboggan problem

  • Thread starter Todd88
  • Start date
  • #1
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Homework Statement


A loaded 305kg toboggan is traveling on smooth horizontal snow at 4.60m/s when it suddenly comes to a rough region. The region is 9.00m long and reduces the toboggan's speed by 1.10m/s.


Homework Equations



What average friction force did the rough region exert on the toboggan?

The Attempt at a Solution



I know you can find the initial conditions of the kinetic energy and then the final conditions given the final velocity. I just don't know how to get the force of the rough region. Any help is appreciated.
 

Answers and Replies

  • #2
djeitnstine
Gold Member
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How much average deceleration of the toboggan was there? You have the initial v, final v and the distance it decelerated by.
 
  • #3
22
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-.12m/s
 
  • #4
djeitnstine
Gold Member
614
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Is that negative velocity? Check your units. Also in the case that is acceleration, then where is the problem of finding the average force of friction? [tex]\bar F_f=m \bar a[/tex] where a is the average deceleration experienced.
 
  • #5
22
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It would be simple but am I correct in saying the average acceleration (deceleration in this case) is -.12m/s^2? Because when I do -.12*305 it is not correct. The friction force would be -37.3N which is incorrect.
 
  • #6
djeitnstine
Gold Member
614
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The correct formula to find acceleration with a distance, and 2 velocities is [tex]v^2_f=v^2_i+2ax[/tex] x=distance, a=acceleration
 
  • #7
22
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Ah of course. I knew that. Thanks!
 

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