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Homework Help: Physics question:Particle leaves the origin

  1. Feb 1, 2010 #1
    1. The problem statement, all variables and given/known data

    A particle leaves the origin with initial velocity v0 = 11i+ 14 j m/s. It undergoes a constant acceleration given by a = –1.2 i + 0.26 j m/s2

    (a) When [i.e., for t greater than zero] does the particle cross the y axis?
    t = s
    (b) What is its y coordinate at that time?
    y = m

    (c) How fast is it moving, and in what direction, at that time?
    v = m/s

    θv = ° from the +x axis

    2. Relevant equations
    Integrals Calculus I believe

    3. The attempt at a solution

    v(t) = ∫ a dt + C = -1.2 t i + 0.26 t j + 11 i + 14 j
    x(t) = ∫ vx dt + C1 = -0.6 t^2 + 11 t
    y(t) = ∫ vy dt + C2 = 0.13 t^2 + 14 t

    a) t=18s
    b) y= 300m
    c)= 22m/s
    d) Can't figure out.... What direction is it moving at that time? ____ degrees
  2. jcsd
  3. Feb 1, 2010 #2
    for d) , you have the x,y components of the velocity vector, and you know that tan(teta) = y/x
    Just imagine it as a triangle.

    Hope this helps
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