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Projectile motion missle

  1. Nov 11, 2014 #1
    1. The problem statement, all variables and given/known data
    A missle is fired vertically up from a ground with an initial velocity of 20m/s. The acceleration at any time is given by dv/dt = -10 + t/2 m/s^2.
    Find the height of the missile after two seconds
    Find the height after four seconds
    the direction the missile is traveling when t = 4

    2. Relevant equations
    Displacement = x
    Velocity = dx/dt
    acceleration = dv/dt

    3. The attempt at a solution

    dv/dt = -10 + t/2 m/s^2
    dx/dt = -10t + t^2/4 + c

    found c to be 20

    x = -5t + x^3/12 + 20t + c

    when t = 0 displacement = 0
    c = 0

    -5t + x^3/12 + 20t

    then I don't know what to do
  2. jcsd
  3. Nov 11, 2014 #2
  4. Nov 11, 2014 #3


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    Please don't make multiple posts of the same HW problem in different forums. It's against the rules of PF and I just wasted time answering your duplicate thread in the Calculus HW forum.
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