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Homework Help: Simple question of understanding projectile motion

  1. Jan 31, 2008 #1
    A projectile is fired at some angle theta to the horizontal with some initial speed vi, and air resistance is neglected. Which statements about the projectile are true? (Select all that apply.)
    ()The projectile is a freely falling body.
    ()Vertical acceleration is 9.8 m/s2, upward.
    ()Vertical acceleration is 9.8 m/s2, downward.
    ()Vertical acceleration depends on theta.
    ()Horizontal acceleration depends on vi.
    ()Horizontal acceleration is zero.
    ()Horizontal acceleration depends on theta.

    Trying to understand key concepts here to this question. Any help appreciated. Thank you!
    Last edited: Jan 31, 2008
  2. jcsd
  3. Jan 31, 2008 #2


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    Depends on what? :confused: Is it angle? What answers do you think are true?
  4. Jan 31, 2008 #3
    Yes..SORRY it is the sign theta. Sorry. Please help!
  5. Jan 31, 2008 #4
    This is very simple. Dont know why i posted it. Projectile motion defined by zero horizontal velocity, acceleration downwards, and freely falling. Sorry too easy guys!
  6. Jan 31, 2008 #5
    Not zero horizontal velocity, zero horizontal acceleration. There is a difference.

  7. May 11, 2011 #6
    hii all
    but why horizontal acceleration is zero???
  8. May 11, 2011 #7
    Because there is no force acting in the horizontal direction.

    The only force here is the force of gravity and that is always vertically downwards.
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