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Homework Help: Pinball Question

  1. Nov 19, 2006 #1
    In a pinball machine, there is a spring, the further back you pull the spring the faster the ball goes. With variables, h, m, R, K and g, what is the spring constant. To get the ball at its minimum speed to go around the boundries of the pinball machine without falling.
  2. jcsd
  3. Nov 19, 2006 #2


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    I can't say I understand the problem completely, but I'm pretty much sure you need to use conservation of energy somehow. Hope that helps.
  4. Nov 19, 2006 #3
    What my teacher is asking is basically the equation for x (spring constant). Theres no numbers involved, but im getting really confused.
  5. Nov 19, 2006 #4


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    While all of the variables you listed are completely understood by you, they are a total mystery to us. Please define your variables.

    Also the minimum speed of the ball is 0, it will not go anywhere at the minimum speed. Please give us a better statement of the problem.
  6. Nov 19, 2006 #5
    Your question appears a little vague. Generally, the spring constant is implied by the variable k (dimensions N/m) and x is the displacement of the spring (in meters) from its equilibrium point. In general, the force Fs of the spring is given by:

    Fs = -kx

    The negative implies the force acts in the opposite direction of the displacement. Some textbooks call this a restoring force.

    If you write the entire question down, perhaps we can be more specific to your needs.

    Hope this helps.
  7. Nov 19, 2006 #6
    Sorry guys, this is all that my teacher gave our class. h is the height of the pinball table like from the spring to the very top of the pinball table. And there is a spring constant (i think he means the stretch of the spring) so that the ball can go at a velocity that would get it around the boundaries of the pinball table without falling off its path. Sorry I cant be more detailed but thats all the info we were given. m is mass, x is spring constant, g is the acceleration.
  8. Nov 19, 2006 #7
    Your looking for how far does the spring stretch back, not the constant.
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