# 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!