Finding the acceleration vector component

[jimmy42]

Homework Statement

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

Homework 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

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?

 

[HallsofIvy]

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

 

[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?