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Homework Help: Help With *Simple* Projectile Motion Problems!

  1. Oct 21, 2008 #1
    1. You accidentally throw your car keys horizontally at 5.0 m/s from a cliff 78 m high. How far from the base of the cliff should you look for the keys?




    2. Maxiumu Horizontal Distance
    Range = [Vi^2]/2 x (2sinTcosT)(G)

    I know that it's a very simple problem, but I need help getting the steps down. I believe that the above formula is correct, but I could be wrong. If the above formula is correct, then how would I find the measurment of angle "T"?

    -shoez
     
  2. jcsd
  3. Oct 21, 2008 #2
    I think you are making it too complicated.

    Write out your variables:

    initial velocity:
    final velocity:
    distance:
    time:
    acceleration:

    based on the variables you have, you should be able to use a distance formula.
    I am unsure which variable you are using right now...

    Hope this helps.
     
  4. Oct 21, 2008 #3

    Well, it's a bit too late, I just submitted my final (and incorrect) answer to WebAssign. But here's what I know so far:

    initial velocity: 5.0m/s
    final velocity: (I believe it is irrelevant to the problem at hand.)
    distance: (X)
    time: (?) Unsure how to solve for time in this case.
    acceleration: 9.8m/s (Gravity)

    My teacher is a great guy, but he recently emigrated from Pakistan and has a very thick accent, which makes it difficult to understand him. I'm sure he instructed us to do solve the problems correctly, but I didn't come away with much on this subject.
     
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