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Homework Help: Questions about Projectiles

  1. Oct 3, 2012 #1
    I have a few questions about projectiles that I just want to verify that my calculations and working out is correct.

    A bullet is fired horizontally from a rifle at 250 m s -1. after travelling 100m the bullet strikes a target

    Calculate the time take for the bullet to strike the target
    Calculate the downward component of velocity of the bullet when it strikes the target

    S= ut

    For the first one I did
    100 = 250t
    t =0.4 s

    And the second
    Since the initial vertical velocity is 0
    u = 0
    t = 0.4
    a = 9.8

    v = u + at
    v = 0 + 9.8 x 0.4
    v = 3.92 m s -1

    Another question is

    Simultaneously a ball is thrown horizontally from a height and another is dropped from rest at the same height , which ball hits the ground first?

    My answer.

    Both balls hit the ground at the same time since the initial vertical velocity of both balls is 0 they both free fall with the same acceleration.

    Are these answers right because I do not have the answers to them
  2. jcsd
  3. Oct 3, 2012 #2

    Doc Al

    User Avatar

    Staff: Mentor

    Looks good to me.
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