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Finding acceleration of bike

  1. Apr 4, 2009 #1
    greetings all

    here is my question:
    Starting from rest, a cyclist coasts down the starting ramp at a professional biking track. if the ramp has the minimum legal dimensions (1.5m high and 12m long), find the acceleration of the cyclist, ignoring friction.

    i am having a hard time figuring this out. i use the pathagorus theorum to get the length of my track, 12.1m (also the hypoteneuse) but after that i am lost.
    the only force i know is gravity. am i missing something here?
     
  2. jcsd
  3. Apr 4, 2009 #2

    Hootenanny

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    HINT: What is/are the force(s) acting on the bike?

    Edit: Ahh, after re-reading your post I see that you have already figured out that the only [net] force acting is that of gravity. So, the only force that is going to make the bike accelerate is gravity.

    What is the component of the gravitational acceleration acting down the ramp?
     
    Last edited: Apr 4, 2009
  4. Apr 4, 2009 #3
    thats just it. it doesnt say.

    there is a part b and c to the question but they dont seem pertinent to a
    (but i will give them to you now anyways, maybe they are)

    b) the acceleration of the cyclist if all sources of friction yeild an effective coefficient of friction of 0.11

    c) the time taken to reach the bottom of the ramp, if friction acts as in b
     
  5. Apr 5, 2009 #4

    Hootenanny

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    Can you work out the component of the acceleration down the ramp?

    Do you know how to resolve vectors into their components?
     
  6. Apr 5, 2009 #5
    i dont think i do.
    what does it entail?
     
  7. Apr 5, 2009 #6

    LowlyPion

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    Maybe this will help?
    http://www.glenbrook.k12.il.us/gbssci/Phys/Class/vectors/u3l3e.html [Broken]
     
    Last edited by a moderator: May 4, 2017
  8. Apr 6, 2009 #7
    that helps a lot. thank you.
     
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