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Mechanics question

  1. Aug 30, 2005 #1
    This was one of my homework assignments...
    I wanted to know if my steps taken are correct.
    Thanks for any feedback.

    A ball rols down a ramp and travels a distance of 3.00 m in 2.05 seconds. Find (a) what is the ball's acceleration? (b) what is the ball's final speed at the bottom of the ramp? And (c) what is the ball's average speed going down the ramp?
    (a) I thought I'd use the formula a = s/t^2 where s = distance, 3m, and t = time, 2.05s.
    (b) I thought I'd multiply what I've gotten for acceleration by 2.05s.... or is this a conceptual thing where it's assumably 0? I don't know.....
    (c) Average speed I'm guessing is the same as (b).
  2. jcsd
  3. Aug 30, 2005 #2


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    s = (1/2)at^2 not at^2

    average speed is (u + V)/2
  4. Aug 30, 2005 #3
    Oh, OK...
    I get the 0.5at^2 part, but isn't average speed total displacement over total time rather than the arithmetic mean of the 2 velocities? :\
  5. Aug 30, 2005 #4


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    yes, if the acceleration is constant both will give the same result.
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