A jet of water of diameter 75 mm having a velocity of 20 m/s strikes normally a flat smooth plate. Determine the thrust on the plate (i) if the plate is at rest and (ii) if the plate is moving in the...

Fluid Mechanics Force
Question:
A jet of water of diameter 75 mm having a velocity of 20 m/s strikes normally a flat smooth plate. Determine the thrust on the plate (i) if the plate is at rest and (ii) if the plate is moving in the same direction as the jet with a velocity of 5 m/s. Also determine the work done per second on the plate in each case and the efficiency of the jet when the plate is moving.
Solution:
1) Force on Flat Vertical Plate When it is not moving:
Force= rate of change of momentum in the direction of the moving water
But since...