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Homework Help: Homework Question: Forces on an incline

  1. Dec 9, 2015 #1
    • Member warned to use the formatting template for homework posts.
    A 10.0 kg object is released from the top of an incline with a height of 1.00m. The incline makes a 15.0 degree angle with the horizontal. If the speed of the object is measured to be 3.00m/s at the bottom of the incline, what was the constant frictional force (Fk) along the incline?

    I have tried everything I can think of to solve this but cannot find the correct solution. The given answer was -13.7N.

    I started with a force diagram and then I tried setting the x and y forces equal to zero and solving for that but got lost. Any help would be appreciated!
  2. jcsd
  3. Dec 9, 2015 #2
    Post them here.
  4. Dec 9, 2015 #3
    Post what here?
  5. Dec 9, 2015 #4
    Your workings.
  6. Dec 9, 2015 #5


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    You have initial and final velocity as well as the displacement. Can you find the net force on the object?
  7. Dec 9, 2015 #6
    Here is the work. I do not understand how this would help find Fk and I do not understand where the velocity has to do with this problem.

    Attached Files:

  8. Dec 9, 2015 #7


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    Just focus on the forces along the incline. The velocities and displacement will help you find the net force (along the incline). From the diagram, you can write the equation for the net force and plug in the values known to you to calculate the frictional force.
  9. Dec 9, 2015 #8
    The object is subject to constant force thus constant acceleration.
    You know the length travelled and both initial and final velocity.
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