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Homework Help: 2-d Problem

  1. Sep 26, 2008 #1
    1. The problem statement, all variables and given/known data
    The vector position of a particle varies in time according to the expression r = (7.40 i - 6.60t2 j) m.
    (a) Find expressions for the velocity and acceleration as functions of time. (Use t, i, and j as necessary.)
    v =
    a =
    (b) Determine the particle's position and velocity at t = 2.00 s.
    r =
    v =

    2. Relevant equations
    kinematic of 2-dimen
    r= v/t

    3. The attempt at a solution
    I found (b) r.. but i have no clue how to start part (A), i thought since R = V/t then
    r =(7.40i - 6.60t^2)/ t but that was wrong.. so I'm thinking that r should be change into something. Any help would be great
  2. jcsd
  3. Sep 26, 2008 #2


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    Homework Helper

    What is the definition of Velocity and Acceleration with respect to distance and time?
  4. Sep 26, 2008 #3
    r/t is average velocity. your trying to find the instaneous rate of change. which means its time to put that calc 1 to use!
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