# Finding the acceleration vector component

1. Mar 2, 2012

### jimmy42

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

A ball travels vertically upward with quadratic air resistance, find the acceleration component.

2. Relevant equations

So, I have x pointing vertically downward and

C=0.20 D = Diameter V=velocity

W= -mgi
R = -C^2D^2V^2

F=ma

ma= -mg-C^2D^2V^2

3. The attempt at a solution

a(t)= dv/dt

dv/dt = (-mg-C^2D^2V^2)/m

After doing the integration it seems not to make any sense. Any help where I have gone wrong? Am I along the right lines?

2. Mar 2, 2012

### HallsofIvy

Staff Emeritus
Well, why are you integrating? The problem, according to you, asks for the acceleration, not the velocity.

3. Mar 3, 2012

### jimmy42

OK, I think that just got me the equation for the acceleration of a resisted projectile

r(t)= -g - (c*D^2*v/m)

So, differentiating this twice should give the acceleration componet? I know the answer I should get and it does not match. Any help?