Physics Question, Please Help!?

Children sometimes play with water rockets, in which an inner compartment is partially filled with water. The air pocket above the water is pressurized using a small pump. When the rocket is released from the pump, it flies upward at an initial velocity of 17 m/s as water exits through a nozzle at the bottom that has a radius of 2.5 mm. If the density of the water is 999 kg/m3, what is the initial thrust of the rocket?