# What was the car's velocity at t=0?

1. Sep 20, 2009

### indietro

1. The problem statement, all variables and given/known data
A car accelerates at 1.75 m/s2 along a straight road. It passes two marks that are 30.3 m apart at times t=3.80 s and t=5.15 s. What was the car's velocity at t=0?

2. Relevant equations

3. The attempt at a solution
Im actually not quite sure how to approach this question. Is there some way that i can find the velocity at the beginning of the time interval that is given?

2. Sep 20, 2009

### willem2

Re: Velocity

What is the average speed over the interval from 3.8s to 5.15 s?

exactly when does the car have this average speed?

3. Sep 20, 2009

### indietro

Re: Velocity

the average velocity over that time interval is 22.4 m/s. but im not sure what you mean by:

4. Sep 21, 2009

### willem2

Re: Velocity

if the car goes has speed $v_i$ at the start of the interval and $v_f$ at
the end of the interval, its average speed is $(v_i + v_f)/2$. The speed at _______
is also $(v_i + v_f)/2$. (with constant acceleration)

5. Sep 21, 2009

### indietro

Re: Velocity

so the middle of the interval (4.48s) would also have the velocity of 22.4 m/s ??