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Ball and Ramp. Kinetic Energy. Friction.Angular Momentum and Velocity.

  1. Dec 12, 2011 #1
    1. The problem statement, all variables and given/known data

    http://landau.physics.fsu.edu/capstick/teaching/2048C-Fall11/Final/Spring09.pdf

    2. Relevant equations

    U_g= mgh
    K.E=1/2mv^2 + 1/2Iw^2
    U_gi=KE_f
    I=1/2MR^2

    3. The attempt at a solution

    I got as far as far as d then realized that i didn't do anything to include the friction, im unsure how to include the friction.

    For A i know the total kinetic energy at the bottom of the ramp has to be equal to the potential energy at the top but what im not sure how to account for the energy lost by heat ie friction. how fast is the ball moving i would use mgh=1/2mv^2 + 1/2Iw^2 and plug in the inertia for a solid cylinder and solve for v
    then i would plug v in to find the angular velocity and would velocity to find momentum*r to find angular momentum.

    then d says to assume there is no friction.
    HELP !
     
  2. jcsd
  3. Dec 12, 2011 #2
    Also let me know if the link works. Thanks
     
  4. Dec 12, 2011 #3
    "For A i know the total kinetic energy at the bottom of the ramp has to be equal to the potential energy at the top but what im not sure how to account for the energy lost by heat ie friction. how fast is the ball moving i would use mgh=1/2mv^2 + 1/2Iw^2 and plug in the inertia for a solid cylinder and solve for v
    then i would plug v in to find the angular velocity and would velocity to find momentum*r to find angular momentum".

    What you state above is correct except for the part about heat. In this problem you would assume there is no sliding so no heat is generated. If there is no sliding, no heat is generated.

    For the case of no friction, think about what makes the cylinder rotate.
     
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