Homework Help: Speed/velocity physics problem

1. Nov 16, 2008

halo9909

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. Nov 17, 2008

Mentallic

Re: speed/velocity

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

Using $$\Delta x=v_{x}t$$ where:
$$\Delta x$$=displacement
$$v_{x}$$=horizontal velocity
$$t$$=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: $$v_{x}=\frac{\Delta x}{t}$$ 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