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I'll start this off for you.
1st estimate the volume of water per second.
I would do this by guessing how long it would take your hose to fill a tank of known volume.
Then guess the diameter of the inside of the hose pipe, and from that the internal cross sectional area.
Then guess the diameter of the nozzle outlet, and hence its cross section area.
Then, you know that the volume of water passing through the pipe and nozzle is equal; and is equal to the cross section area times the velocity.
From this you will get the change in velocity of the water as it passes through the nozzle.
Acceleration is rate of change of velocity.
I would add that I'm intrigued as to exactly what, at "Masters Level", this question is designed to test.