physics
posted by Angela .
A model rocket is propelled upward by a cylinder of compressed water. The cylinder emits water at a rate of 0.050 kg/second with an exit speed of 80.0 m/s. Initially, the rocket has a mass of 0.15 kg, including the water cylinder. What is the rocket's initial upward acceleration? Don't forget to add in the downward force of gravity.

at liftoff.
Remember force is the rate of change of momentum.
mg+(masswater+massrocket)a=fuelrate*velocity
solve for a