Inclined plane, Calculate friction force

  • #1
TheRedDevil18
408
1

Homework Statement



work.jpg


Homework Equations



Wnet = Ek

The Attempt at a Solution



1) That was fine.
2) I just want to confirm if this answer is right?, I got 12.28N. Used work energy theorem.

Sorry for double post, edited the title
 

Answers and Replies

  • #2
haruspex
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Homework Statement



work.jpg


Homework Equations



Wnet = Ek

The Attempt at a Solution



1) That was fine.
2) I just want to confirm if this answer is right?, I got 12.28N. Used work energy theorem.

Sorry for double post, edited the title

Seems a bit high. Pls post your working.
 
  • #3
TheRedDevil18
408
1
Seems a bit high. Pls post your working.

Sorry my mistake, forgot something in my calculation. Anyway here's my working

Wnet = Ek
Wg + Wf + Wn = 1/2*m(vf^2 - vi^2)
(5*9.8*sin30*20) - 20Ff + 0 = 1/2*5(12^2 - 6^2)...That 20 is the length of the incline
Ff = 11N...Now correct?
 
  • #4
haruspex
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Sorry my mistake, forgot something in my calculation. Anyway here's my working

Wnet = Ek
Wg + Wf + Wn = 1/2*m(vf^2 - vi^2)
(5*9.8*sin30*20) - 20Ff + 0 = 1/2*5(12^2 - 6^2)...That 20 is the length of the incline
Ff = 11N...Now correct?

Yes, that looks right.
 

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