Step-by-step explanation:
Initial speed of the incident water stream, u = 16 m/s
Final speed of the exiting water stream, v = -16 m/s
The mass of water per second that strikes the blade is 48.0 kg/s.
We need to find the magnitude of the average force exerted on the water by the blade. The force acting on an object is given by :

Here,


So, the magnitude of the average force exerted on the water by the blade is 1536 N.