Very basic physics problem

[AcecA]

Homework Statement

A particle is moving along a straight line such that its acceleration is defined as a = (-2v) m/s^2, where v is in meters per second. If v = 20 m/s when s = 0 and t = 0, determine the particle's velocity as a function of position, and the distance the particle moves before it stops.

Homework Equations

Basic kinematics equations

The Attempt at a Solution

I tried using dt = dv/a and integrating that, and I got t = (ln20 - lnv)/2, then I tried substituting it into s = s0 + v0t + (1/2)at^2, and now I'm stuck. Any help would be appreciated. Thanks :)

 

[rock.freak667]

Use the fact that

$$a= \frac{dv}{dt}=v \frac{dv}{ds}$$

this will help you get velocity in terms of displacement.

 

[AcecA]

Oh right. Thanks a bunch :)