Work done problem

  • Thread starter Jake4
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  • #1
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Homework Statement



A block is being slid along a rough surface by a force of 94.6 N forming an upward angle with the horizontal of 29 degrees. The mass of the block is 18.7 kg. It is displaced 70.6 m, and the coefficient of friction is .186

what is the total work done by the force.


Homework Equations



Work = (Fnet)(displacement)

friction = coefficient(Fnormal)


The Attempt at a Solution


I drew a free body diagram, and derived these equations:

Fnormal + 94.6sin(29) = mg
Fnet = 94.6cos(29) - friction

From this, I got that Fnormal = 137.3970099 N
friction = 25.55584385 N
Fnet = 57.18318045 N

thus, 57.18318045 N x 70.6 m = 4037.13254 J

Our online program for homework is telling me this is incorrect >.< I'm really not sure what to do.
 

Answers and Replies

  • #2
tiny-tim
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Homework Helper
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Hi Jake4! :smile:

A block is being slid along a rough surface by a force of 94.6 N forming an upward angle with the horizontal of 29 degrees. The mass of the block is 18.7 kg. It is displaced 70.6 m, and the coefficient of friction is .186

what is the total work done by the force.

Fnet = 94.6cos(29) - friction

Fnet = 57.18318045 N

thus, 57.18318045 N x 70.6 m = 4037.13254 J

read the question :rolleyes:

it doesn't ask for the total work done by the net force. :wink:
 
  • #3
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>.<!

wow, got it now... frustrates me more when it's simple misunderstandings like that!

thanks :)
 

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