1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Pinball machine problem on energy/power/work

  1. Feb 2, 2014 #1
    1. The problem statement, all variables and given/known data
    A pinball machine has a spring that loads up, and shoots a small ball up a shallow incline. The mass of the pinball is .05kg. The incline for the pinball is 15 degrees. Assume no friction exists along the distance over which the spring applies its force. The coefficient between the ball and sloped surface is .15. The speed of the ball at the top of the incline is 3m/s. The spring is compressed .08 m. The length of the incline is .75m. What is the value of the spring constant?


    2. Relevant equations

    PE=mgh
    KE=.5mv^2
    KE+PE=w
    Spring constant

    3. The attempt at a solution

    .05(9.8)h=PE

    KE=.5(05)(9)
     
  2. jcsd
  3. Feb 2, 2014 #2
    This is another conservation of energy problem: looks like you have both kinetic energy and potential energy being gained, whereas elastic potential energy from the spring is being lost. You can calculate the potential energy of a spring with this equation:

    [itex]U_{e} = \frac{1}{2}k(x_f^{2} - x_i^{2})[/itex], where [itex]x_f[/itex] is the final extension of the spring, and [itex]x_i[/itex] is the initial extension, and [itex]k[/itex] is the spring constant.
     
  4. Feb 2, 2014 #3
    How would you go about solving xf and xi???
     
  5. Feb 2, 2014 #4
    Just think of what they mean: final extension is just that: final extension. After the spring decompresses and launches the ball, it's not compressed anymore, so final extension is zero. Initial extension is also just that. Look at givens in the problem for how much the spring is compressed to start.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Pinball machine problem on energy/power/work
Loading...