Falling body in resistive medium with quadratic drag

[eyvhgi557r]

1. The motion of a body falling from rest in a resistive medium is dv/dt = Bv - Av^2.


2. Find it's initial acceleration.
Find the velocity at which the acceleration becomes zero.


3. B and A are constants.

dv/dt = acceleration = Bv - Av^2.

vf = vi + at
vf = 0 + Bv - Av^2(t)
vf = Bv - Av^2(t)

Where am I going with this?

 

[tiny-tim]

Hi eyvhgi557r!

1. The motion of a body falling from rest in a resistive medium is dv/dt = Bv - Av^2.
…
vf = vi + at
vf = 0 + Bv - Av^2(t)
vf = Bv - Av^2(t)

Where am I going with this?

hmm … nowhere!

those equations only apply to uniform acceleration …

you need to solve dv/dt = Bv - Av^2 in the usual way.