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Homework Help: Distance traveled by projectile

  1. Mar 27, 2014 #1
    1. The problem statement, all variables and given/known data
    Suppose you have a projectile of 120g.
    Suppose that projectile is accelerating at 9186.05 m/s/s for 0.129 seconds, to a velocity of 12150 m/s.
    Factoring in a 20% drop in Velocity from aerodynamics and friction, it accelerates to roughly 9750 m/s.

    What distance did the projectile travel in the 0.129 seconds that it was accelerating? Please provide relevant units of measurement.

    2. Relevant equations

    3. The attempt at a solution
    I plugged everything into the above equation, but I don't feel like it is a realistic value, and I'm not sure of what unit is used (m, km, cm, etc...)
  2. jcsd
  3. Mar 27, 2014 #2
    What value did you get?

    100g acceleration is huge!
  4. Mar 27, 2014 #3
    When I plugged everything into the equation, it looked like:
    d = (12150)(0.129) + 1/2(94186.05)(0.129)^2
    which resulted in 2351.025
    I don't know if that's cm or m or km, but thats the number that came out out of the equation
  5. Mar 27, 2014 #4
    Try doing it again but this time show all the units explicitly.
  6. Mar 27, 2014 #5
    d = (12150 m/s) (0.129 s) + 1/2 (94186 m/s/s) (0.129 s)^2
  7. Mar 27, 2014 #6
    Ok, can you see which units might cancel with each other?
  8. Mar 27, 2014 #7
    I don't think I do :(
  9. Mar 27, 2014 #8
    Well that's alright. In your equation, what are all the units you are dealing with? Just list them all...
  10. Mar 27, 2014 #9
    Velocity - m/s
    Acceleration - m/s^2
    Time - s
    distance - ?
  11. Mar 27, 2014 #10
    Ok, but each of these can be broken down further into their basic dimensional units also.
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