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Homework Help: Help displacement problem

  1. Jun 30, 2011 #1
    1. The problem statement, all variables and given/known data

    Determine the displacement of this particle from t=1s to t=3s

    r=-(5,0m/s)t i + (10,0m/s^2)t^2 j + (7,0m -(2,0m/s^3)t^3) k

    2. Relevant equations

    3. The attempt at a solution
    I dont have an idea how to do this if I should to it by replacing t by 1 and then getting the magnitude of the vector for example. or should i get the value of t = 1 by each component alone and substract the components of 3 - the components of 1 ?

    I must finish this soon thanks for the help in advance
  2. jcsd
  3. Jun 30, 2011 #2
    the equation represents the position vector in the form of coordinates.make t=1and t=3,you will get two position vectors (-5,10,5)and(-15,90,-20).use the knowledge of vector of the form of coordinates and you will get the answer
  4. Jun 30, 2011 #3
    Now I must only get the magntitude of the vectors? thanks
  5. Jun 30, 2011 #4
    you may get the magnitude of the vector of displacement by using pythagorean theorem
  6. Jun 30, 2011 #5
    thanks a lot
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