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Homework Help: How fast is a falling object going without riction

  1. Nov 8, 2007 #1
    An object falls from rest for a distance of 25 m. If there was no air friction, how fast was it going at that distance?

    I'm not sure but I would imagine v=(25m)(9.8m/s^2)= 245m/s ? which seems quite high to me so I know I am not calculating it correctly.
     
  2. jcsd
  3. Nov 8, 2007 #2

    Dick

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    You sure aren't. The units of your v are m^2/sec^2. That's not a velocity. It's a velocity squared. Hint, hint. There's a shortcut formula you can use, or you can just do straight kinematics. Like x=x0+v0*t+(1/2)*a*t^2.
     
  4. Nov 8, 2007 #3
    so should I just take the square root of 245 then?
     
  5. Nov 8, 2007 #4

    Dick

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    Nope. There's another dimensionless factor you are missing. If you are going to go for a shortcut, I think you should find the correct formula, there is one that relates initial velocity, final velocity and distance traversed.
     
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