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Homework Help: Magnitude of average velocity and derive equation

  1. Sep 15, 2009 #1
    These 2 questions are confusing me, I have some idea about what to do, can someone help?

    Question 1
    1. The problem statement, all variables and given/known data
    Consider a circular track with a radius of 200 meters, suppose it takes 2 minutes to run from her starting point to the opposite side of the track. What is the magnitude of her average velocity over this 2 minute interval? What is her average speed over the same interval?

    3. The attempt at a solution
    I did 400m/120s and got 3.33 m/s, and for speed 400m/120s = 3.33 m/s (should I be putting significant figures also or something?)

    Question 2
    1. The problem statement, all variables and given/known data
    Derive Vf^2=Vi^2+2ad

    2. Relevant equations

    (I think this is equation for velocity of an object)

    3. The attempt at a solution

    I thought that you would treat it like a derivative and comes out to 2Vi+2, but I got it wrong.
  2. jcsd
  3. Sep 15, 2009 #2


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    Homework Helper

    Find the length of the track along the circular path.Now find her velocity. This will be her average speed.
    Initially her velocity in one direction. When she reaches the diaametrically opposite point, what is the direction of her velocity and what is the magnitude of her velocity?
    Now find the average velocity.
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