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Physics - HELP!

  1. Sep 22, 2003 #1
    [SOLVED] Physics - HELP!

    Hey guys,

    Currently taking Grade 12 Advanced Placement Physics. I'm craming for a kinetics test tomorrow, which I will do reasonably well. However, I am still stumped on solving Motion of 2 Dimensions using the "Component Technique". I am able solve it using the Sine and Cosine laws, but I have to be able to solve it using both.

    If anyone could help me out by taking a shot at explaining it, it would be very much appreicated.

    A sample problem:

    A passenger in a hot-air balloon throws a ball with an initial unknown velocity. The ball accelerates at 9.8m/s/s [down] for 2.0s, at which time its instantaneious velocity is 24m/s [45 degrees below the horizontal]. Determine the ball's initial velocity.

    Again, any help would be greatly appreciated.
    Last edited by a moderator: Sep 22, 2003
  2. jcsd
  3. Sep 22, 2003 #2
    After 2 seconds,
    Vx^2 + Vy^2 = 24^2

    With the 45 degree angle thing, conclude Vx = Vy at this time

    Vx = (576/2)^0.5
    = 16.97ms-1
    Vy = 16.97ms-1

    Assume horizontal velocity unchanged over 2s. Ux = Vx = 16.97ms-1

    Uy = Vy - 9.81*2
    = - 2.63ms-1

    Note: 'U' refers to initial velocities, 'V' to end ones, 'x' to horizontal direction, 'y' to vertical.

    Initial speed = 17.17ms-1
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