## Motion with changing mass

1. The problem statement, all variables and given/known data
http://www.physicsforums.com/attachm...1&d=1318764025

2. Relevant equations
F=m$\frac{dv}{dt}$-v$\frac{dm}{dt}$

3. The attempt at a solution
It seems part b is trivial. Obviously, the propellsion force is constant. To find F, just subs m=m/2

I am not sure wheather I am right.

http://www.physicsforums.com/attachm...1&d=1318764025
Attached Thumbnails

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 Why should the propulsion force be constant? As the water level goes down the water pressure at the bottom of the bucket will be lower so the water velocity will be less?

 Quote by Spinnor Why should the propulsion force be constant? As the water level goes down the water pressure at the bottom of the bucket will be lower so the water velocity will be less?
I know the force depends on the ejected speed, but the question state that its speed is constant, that's why I say it is constant and the whole question becomes very esay.