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Acceleration question BASIC PHYSICS HELP

  1. Feb 1, 2010 #1
    Acceleration question BASIC PHYSICS HELP :(

    Question1: A ball rolls with an acceleration of 20.5m/s^2. If it stops after 7s, what was its initial speed ? (Answer 3.5 m/s )

    Question2: A wheelchair marathoner has a speed of 5m/s after rolling down a small hill in 1.5 s. If the wheelchair underwent a constant acceleration of 3m/s^2 during the descent , what was the marathoners speed at the top of the hill ? (Answer: 0.5m/s)

    Question3:

    What does it mean when it says in a problem: "at a 45* angle from due East and from due North" ?

    Please, please help me figure those questions out with explanation.
    Very much appreciate your help.


    Thank you in advance
     
  2. jcsd
  3. Feb 1, 2010 #2
    Re: Acceleration question BASIC PHYSICS HELP :(

    Hi,

    When I took physics for the first time in high school many years ago I purchased The Cartoon Guide to Physics by Larry Gonick. I don't think I would have done as well as I did without it. The cartoons were amusing and helped me to visualize the problems which made solving them that much easier!

    I don't want to take away from your experience of solving the problems for yourself but I will suggest that they may require the use of multiple formulae:) If you need them, you can get them here: http://www.physics247.com/physics-tutorial/acceleration.shtml

    Hope this helps!
     
  4. Feb 2, 2010 #3

    Redbelly98

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    Re: Acceleration question BASIC PHYSICS HELP :(

    Welcome to Physics Forums, AbovenBeyond and BrainGirl.

    AbovenBeyond, what is the definition of acceleration? What equation is given along with that definition?
     
  5. Feb 2, 2010 #4
    Re: Acceleration question BASIC PHYSICS HELP :(

    Hello,

    Acceleration = (change in velocity) /( change in time)
    20.5m/s^2= (change in Velocity) / 7s
    =143.5m/s
     
  6. Feb 3, 2010 #5

    Redbelly98

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    Re: Acceleration question BASIC PHYSICS HELP :(

    You're correct, the answer 3.5 m/s is wrong.
     
  7. Feb 5, 2010 #6
    Re: Acceleration question BASIC PHYSICS HELP :(

    Can someone please explain to me how to do this question, even better solve it and explain the steps.. I find it quite difficult.
    Question2: A wheelchair marathoner has a speed of 5m/s after rolling down a small hill in 1.5 s. If the wheelchair underwent a constant acceleration of 3m/s^2 during the descent , what was the marathoners speed at the top of the hill ? (Answer: 0.5m/s)

    HELP :((
     
  8. Feb 5, 2010 #7
    Re: Acceleration question BASIC PHYSICS HELP :(

    Did you draw a diagram(label what happens where and when , velocityInital= ? , velocityFinal=? , Acceleration=? StartPosition =? , EndPosition=? That always helps me in addition to putting closely related equations next to the drawing.
     
  9. Feb 6, 2010 #8

    Redbelly98

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    Re: Acceleration question BASIC PHYSICS HELP :(

    Moderator's note:
    • Separate homework questions should be posted in a new thread.
    • Homework help requests should include relevant equations and an attempt at a solution.
     
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