Bottle Rocket Velocity: Constant Force, Increasing Rate

[jerryez]

Homework Statement

A bottle rocket is launched in the air. The black powder, which propels it, burns leaving an exhaust trail mainly consisting of CO2 gas. If the force propelling the rocket is constant, the rate of change in its velocity INCREASES.

Can someone please explain why the change in its velocity increases. I was thinking since the force propelling the rocket is constant the rate of change in its velocity is ZERO. ?

Homework Equations

The Attempt at a Solution

 

[ehild]

The black powder burns out so the mass of the whole rocket decreases. ehild

 

[ehild]

The black powder burns out so the mass of the whole rocket decreases.


ehild