Velocity, position and time

1. Sep 9, 2009

Loppyfoot

1. The problem statement, all variables and given/known data
A particle moving along an x-axis with constant velocity is at the point x=1 when t=2 and is at the point x=5 when t=4. Find the velocity of the particle if x is in meters and t is in seconds. Find an equation that expresses x as a function of t.

2. Relevant equations

3. The attempt at a solution
I got the first part. (4-2)/(5-1) = 0.5m/s. Now, how do I get the equation that expresses x as a function of t?

2. Sep 9, 2009

kuruman

You got the first part by assuming that the object covers equal distances in equal times. Can you write an equation that expresses that?

** Edit **

Actually you did not get the first part. You divided time interval by displacement.

Last edited: Sep 9, 2009
3. Sep 9, 2009

Loppyfoot

Oh, so would the velocity be 2?
Ok, so x=2t+?
So, it is 2t-3.
Right?

Last edited: Sep 9, 2009
4. Sep 9, 2009

kuruman

Yes, x is directly proportional to time, the constant of proportionality being the velocity. To find the velocity, you need to do part (a) correctly. The y intercept in this case is the position of the particle at time t = 0.

5. Sep 9, 2009

Loppyfoot

So when time = 0, the particle is at coordinate x=-3.

6. Sep 9, 2009

You got it.

7. Sep 9, 2009

Loppyfoot

Thanks for notifying me of my mistake!