The momentum equation based on Newton’s 2nd law of motion states that the algebraic sum of external forces applied to control volume of fluid in any direction equal to the rate of change of momentum in that direction. The external forces include the component of the weight of the fluid and of the forces exerted externally upon the boundary surface of control volume. If a vertical water jet moving with velocity ‘V’ made to strike a target (Vane) which is free, to move in vertical direction, force will be exerted on the target by the impact of jet. Applying momentum equation in z- direction, force exerted by the jet on the vane, Fz is given by F = ρQ (Vzout- VZ in) For flat plate, Vz out= 0 Fz = ρQ (0-v) FZ = ρQv For hemispherical curved plate, vz out= -v, vz in= v Fz = ρQ [v+ (-v)] FZ = 2 ρQv Where Q= Discharge from the nozzle (Calculated by volumetric method) V= Velocity of jet = (Q/A)

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