Changing Mass and Constant Force: Is it Really That Simple?

[athrun200]

Homework Statement

https://www.physicsforums.com/attachment.php?attachmentid=40057&stc=1&d=1318764025"

Homework Equations

F=m$\frac{dv}{dt}$-v$\frac{dm}{dt}$

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.

https://www.physicsforums.com/attachment.php?attachmentid=40058&stc=1&d=1318764025"

 

[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?

 

[athrun200]

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.