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Total work done

  1. Jul 19, 2011 #1
    A child on a sled (having a combined mass of 47.0 kg) is pulled by a force directed along a rope that makes a 45 degree angle with the horizontal axis. the force exerted on the rope is 100.00 N. the force of friction acting on the sled is 30.0 N. if the child is pulled a distance of 10.0 m along a level field, determine the total work done on the child and the sled.

    Attempt:
    Given:
    d: 10.0 m, F:100.0 N (45 degrees), Ff: 30.0 N (180 Degrees)

    W=F(costheta) . deltad
    W= 100.00 N X cos45 X 10.0m
    W=707J
    that would be just for the rope

    would i have to do the same calculation using the Ff now? then add both numbers to get total work done?

    It also asks for the final speed at the end of 10.0 m

    HELP PLEASE!
     
  2. jcsd
  3. Jul 19, 2011 #2

    Doc Al

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    Staff: Mentor

    Yes.

    Make use of the net work done that you've calculated.
     
  4. Jul 19, 2011 #3
    ok so for the speed, i'd use
    W= (1/2)mv^2 and just rearrange it
     
    Last edited: Jul 19, 2011
  5. Jul 19, 2011 #4

    Doc Al

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    Staff: Mentor

    Good!
     
  6. Jul 19, 2011 #5
    thanks sooooo much. i've never taken physics before and i'm finding that while i understand most concepts, I tend to need a lot of reassurance
     
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