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Homework Help: Circular Motion HW Help

  1. Jan 13, 2012 #1
    Circular Motion HW Help!!!

    1. The problem statement, all variables and given/known data
    Problem: A 4.0kg ball is attached to 0.70m string and spun at 2.0m/s. Calculate the centripetal acceleration of the ball and the centripetal force on the ball.

    2. Relevant equations
    I don't know of any other ones our teacher gave us some worksheets and this is the only one like this !!!!

    3. The attempt at a solution

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Jan 13, 2012 #2
    Re: Circular Motion HW Help!!!

    Hi. This is a relatively simple problem (hence, I can help you solve it).

    First piece of advice, always draw a fbd (free body diagram). It helps to clarify things, and gives you something to visualize.

    Here, you know that the centripetal force is a center seeking force, and the velocity is always tangent to the circle.

    Did you learn an equation in class today, that relates the two values of velocity and radius, to find the centripetal acceleration?

    After you find the acceleration, remember Newton's Second law. F=ma. Once you know acceleration, you can find the centripetal (center seeking) force.

    Try it!
  4. Jan 13, 2012 #3
    Re: Circular Motion HW Help!!!

    yes but do you know what equation I need to use?
  5. Jan 13, 2012 #4
    Re: Circular Motion HW Help!!!

    how do i find acceleration?
  6. Jan 13, 2012 #5
    Re: Circular Motion HW Help!!!

    Centripetal (Radial) acceleration = (velocity^2)/radius
    Centripetal force = mass*centripetal acceleration

    plug the numbers in and you should get the answer.
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