How Is the Average Force on Water by a Turbine Blade Calculated?

[copitlory8]

Homework Statement

A stream of water strikes a stationary turbine blade, as the drawing illustrates. The incident water stream has a velocity of +18.0 m/s, while the exiting water stream has a velocity of -18.0 m/s. The mass of water per second that strikes the blade is 75.0 kg/s. Find the magnitude of the average force exerted on the water by the blade.

Homework Equations

kinematics equations
(PEf - PE0)

The Attempt at a Solution

i have no idea where to start

 

[ehild]

Think of impulse and change of momentum.

ehild