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Homework Help: Spring powered putting machine

  1. Oct 12, 2013 #1
    1. The problem statement, all variables and given/known data

    I am currently enrolled in a Engineering Drafting class. We are working on a group project where we are making a putting machine. We decided on a spring powered device. The ramp's measurements look like this where the goal is to get it into the hole at the end of the ramp.
    http://i.imgur.com/o4q0D9X.jpg Its a golf ball rolling on astroturf. Heres the information he gave me when I told him I don't understand fully. http://i.imgur.com/dDhOKrO.jpg
    And this is the information when he first explained it. http://i.imgur.com/A9zEuJu.jpg

    From my understanding. The Professor wants the amount of force required to hit the ball into the hole. And also how much force the spring is hitting the ball with. I've only dipped my toes into the great ocean of physics and I'm still in pre-calc. This all seems very complicated to me and I have a feeling it's not that hard. Thanks in advance for your help.

    Sorry for not embedding the pictures. When I did they were too big.

    2. Relevant equations

    This is for calculating the coefficient of friction.

    MgH - [itex]M[/itex] /distance = 0
    Mg = Mass of golfball = .099lb
    H = Height = .038ft
    [itex]M[/itex] = coefficient of friction
    Distance = 1.65ft (average of 6 tries)
    18.4375, 19, 19.3125, 20, 20.0625, 20.4375, 21.3125

    3. The attempt at a solution

    (.099 * .038) - ([itex]M[/itex]/1.65) = 0
    .003762 - [itex]M[/itex]/1.65 = 0
    -[itex]M[/itex]/1.65 = -.003762
    [itex]M[/itex]/1.65 = .003762
    [itex]M[/itex] = .00621
    Last edited: Oct 12, 2013
  2. jcsd
  3. Oct 12, 2013 #2


    User Avatar

    Staff: Mentor

    Welcome to the PF.

    So the golf ball needs to roll to the right up the ramp to get into the hole? And you need to calculate how much force to store in a spring plunger to make that happen? Then why are you calculating a mass M? Sorry that I'm not tracking what you are doing.

    You should also include the energy that is invested in the rolling of the ball (that involves the moment of inertia of the ball). The energy of the ball includes the KE of the linear velocity, the PE of the height of the ball above some reference height, and the energy in the rotation of the ball. Does that help?

    EDIT -- Sorry, I was confused by your multiple uses of M -- why are you calculating the coefficient of friction? You want to calculate the force or impulse or energy stored in the spring pluger, right?
  4. Oct 15, 2013 #3
    I was following the equations that the professor wrote on the board. http://i.imgur.com/A9zEuJu.jpg shows the formula on the bottom. Friction energy was coefficient of friction from my understanding. I think I was using the wrong symbol for coefficient of friction. I thought the greek M was for coefficient of friction. The ball with be level with the astroturf pushed out of a tube by a spring. He wants some basic physics in the report. All the formulas he wrote down do not look like basic physics to me, Its something I havent really taken yet. If you guys have any recommendations on a better example of they physics behind this project I will take all recommendations. Thank you.
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