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Homework Help: Speed/velocity physics problem

  1. Nov 16, 2008 #1
    1. The problem statement, all variables and given/known data

    A steel ball rolls with a constant velocity across a table top 1.063 m high. It rolls off and hits the ground +0.229 m horizontally from the edge of the table. How fast was the ball rolling?


    2. Relevant equations

    d=.5at^2
    X=Vxt
    3. The attempt at a solution

    I first did
    1.063=.5(9.8)t^2
    got the time to be .4657 seconds
    then put it in the X=Vxt
    and got Vx to be .4916, and I am not sure where to go from there
     
  2. jcsd
  3. Nov 17, 2008 #2

    Mentallic

    User Avatar
    Homework Helper

    Re: speed/velocity

    You approached the question correctly, but your final result is wrong.

    Using [tex]\Delta x=v_{x}t[/tex] where:
    [tex]\Delta x[/tex]=displacement
    [tex]v_{x}[/tex]=horizontal velocity
    [tex]t[/tex]=time

    the displacement will be the distance it travelled from the edge of the table, the time is what you just calculated, and all that is left is the horizontal velocity.

    Rearrange the formula to make velocity the subject: [tex]v_{x}=\frac{\Delta x}{t}[/tex] and substitute to find your answer.

    EDIT: Sorry your answer was correct, calculator error on my part.
    That is the answer to the question, in metres/second (ms-1)
     
    Last edited: Nov 17, 2008
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