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Deceleration on a Gradient

  1. Oct 24, 2014 #1
    Hi guys, I'm new to this site so forgive me if I'm unfamiliar with any etiquette unique to here. We did a practical exercise the other day in class in which we accelerated a bogey to a certain RPM and then released it to accelerate up a ramp. We were then given a sheet of the measurements I have listed below and told to go home and write a report calculating predicted values for the distance travelled up the ramp and compare the values to the distance we had measured. Friction is negligible.

    1. The problem statement, all variables and given/known data

    Given measurements
    Mid ordinate power values
    Time = 6.3s (from release to maximum potential energy)
    Mass = 0.626 kg
    Initial RPM = 750 RPM
    Distance travelled up slope = 2.27 m
    Height at max distance = 0.04 m

    Measurements calculated/known so far
    Average Power = 1.38 W
    Total Ek = 10.488 J
    Angular velocity = 25pi rad/s
    Angular Ek = 0.8326 J
    Linear Ek = 9.6554 J
    Initial velocity = 5.55 m/s
    Final velocity = 0 m/s

    2. Relevant equations

    E = Pt
    E = 0.5Iw^2 (substituting omega for w)
    E = 0.5mv^2
    v^2 = u^2 + 2as
    F = ma
    F = mg

    3. The attempt at a solution

    Calculated average power, then used E = Pt to determine total kinetic energy.
    Stated that Ek (total) = Angular Ek + Linear Ek
    Used values of mass and radius to calculate inertia for each component. (Values not listed as I'm confodent this is correct.
    Calculated Angular Ek using E = 0.5Iw^2 for each component then summed them for total.
    Calculated Linear Ek using Ek (total) - Angular Ek
    Calculated Initial Velocity using E = 0.5mv^2

    I think I now need to draw a diagram and resolve parallel and perpendicular values for the force?
    Then use F = ma to calculate deceleration?
    Then use v^2 = u^2 + 2as to calculate displacement?

    If someone could confirm/correct my thought process there it would be brilliant.

  2. jcsd
  3. Oct 30, 2014 #2
    Thanks for the post! Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post?
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