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Homework Help: Two dimensional motion - intitial velocity?

  1. Jan 14, 2008 #1
    two dimensional motion - intitial velocity?!?!

    so i have the vertical distance, 8.0 m, and the horizantal distance, 10.0 m, how do i find the initial velocity of the projectile??
  2. jcsd
  3. Jan 14, 2008 #2
    I'm guessing this problem says that something was fired horizontally at an initial velocity v....blah blah, find v. Is that correct?
    Last edited: Jan 14, 2008
  4. Jan 14, 2008 #3
    no :[

    a student threw a ball horizontally out of a window 8.0 m above the ground. it was caught at ground level by another student who was 10.0 m away. what was the initial velocity of the ball?

    no masssss
  5. Jan 14, 2008 #4
    Ok. This is not hard. You have to break the problem up into two parts.

    First, you want to find the time that the ball is in the air. To do this you only consider the vertical motion (You can do this since vertical and horizontal motion are independent of each other). So, initially there was no vertical velocity. using d=v[tex]_{i}[/tex]t + [tex]\frac{1}{2}[/tex]at[tex]^{2}[/tex] you can solve for the time.

    Next, you consider the horizontal motion. Now we know the time and the horizontal distance. We also know that the horizontal velocity will stay constant. Now you can use d=v[tex]_{horiz}[/tex]t and solve for the velocity.

    Hope that helps.
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