# Position, velocity, and acceleration

1. Sep 13, 2009

### riffelr

1. The problem statement, all variables and given/known data

5. A particle moves along the x-axis, with x(t) = 2.00 + 3.00 t – 1.00 t^2.
SI units are used throughout.
(a) What is the position of the particle at t = 3.00 s?

(b) What is the velocity of the particle at t = 3.00 s?

(c) What is the acceleration of the particle at t = 3.00 s?

2. Relevant equations

3. The attempt at a solution

I solved letter a, but I have no idea how to complete letters b and c. Any help would be great.

Thanks.

2. Sep 13, 2009

### pgardn

Take the derivative of the position function with respect to time and you get the velocity function of the object with respect to time. Plug in t =3s. Take the derivative of the velocity function with respect to time and you get the acceleration with respect to time which in this case you will find is a constant.

If you guys have not done calculus and are just doing this on a graphing calculator you can plot the position function and look a the slope at t = 3s and you will get the velocity at t = 3s. Now if your teacher gave you what those constants mean in front of the variable t, you can do the same thing with the velocity v. time and you will see a line. The slope of that line does not change and this tells you the acceleration is uniform through time.

Hope this helps some.

Last edited: Sep 13, 2009