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Homework Help: Energy related problem (includes diagram)

  1. Oct 18, 2012 #1
    1. The problem statement, all variables and given/known data
    A box m = 88 kg is being pulled by a constant force F = 176 N at an angle of θ = 38 degrees.

    m = 88 kg
    θ = 38 degrees
    F = 176 N

    2. Relevant equations


    3. The attempt at a solution

    (a) Write an expression for the work done by force F on the block over a distance d.

    Okay, so for this one I just put in W=Fd. The problem started out with "W=" before showing the blank right next to it, so I assumed it just wanted the work equation. However, this is wrong. I'm not exactly sure how else to figure it out.

    (b) How much work, in Joules, was done in moving the block 5 meters?

    So I did W=Fd again. I multiplied 176*5, got a value of 880 J. Apparently this is wrong, too. Why? Do I need to factor in the angle in which block is being pulled?

    (c) What is the velocity of the box at d = 5 m if the surface is frictionless?
    I'm aware that the equation needed to solve for this is W = mv2/2, since it allows me to solve for velocity, however I don't have that, nor do I have W because I'm guessing that the problem assumes that I need to use the value I got for W in order to solve this problem.

    Any help will be very much appreciated.
    (See attachment for diagram)

    Attached Files:

  2. jcsd
  3. Oct 18, 2012 #2
  4. Oct 18, 2012 #3
    Ah, that made the problem so much easier. Thank you!
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