Net force acting on fluid in the direction of x =Rate of change of momentum in x direction
=Mass per sec×Change in velocity

**DIFFERENCES BETWEEN SOLIDS AND FLUIDS**

The differences between the behaviors of solids and fluids under an applied force are as follows:

i. For a solid, the strain is a function of the applied stress, providing that the elastic limit is not exceeded. For a fluid, the rate of strain is proportional to the applied stress.

ii. The strain in a solid is independent of the time over which the force is applied and, if the elastic limit is not exceeded, the deformation disappears when the force is removed. A fluid continues to flow as long as the force is applied and will not recover its original form when the force is removed.

**MOMENTUM EQUATION**

Net force acting on fluid in the direction of x=Rate of change of momentum in x direction

=Mass per sec×Change in velocity

p1A1-p2A2×cos θ-Fx=ρQ(v2cosθ-v1)

Fx=ρQ(v1-v2cosθ)-p2A2cosθ+p1A1

Similarlt,the momentum in y-direction is -p2A2sinθ+Fy=ρQ(v2sinθ-0)

Fy=ρQv2sinθ+p2A2 sinθ

Resultant force acting on the bend,

Fr=√Fx²+Fy²

**GLOSSARY**

Quantity : Unit

Mass in Kilogram : Kg

Length in Meter : M

Time in Second : s or as sec

Temperature in Kelvin : K

Mole : gmol or simply as mol

**Derived quantities:**

**Quantity : Unit**

Force in Newton (1 N = 1 kg.m/s2) : N

Pressure in Pascal (1 Pa = 1 N/m2) : N/m2

Work, energy in Joule ( 1 J = 1 N.m) : J

Power in Watt (1 W = 1 J/s) : W

Study Material, Lecturing Notes, Assignment, Reference, Wiki description explanation, brief detail

Mechanical - Fluid Mechanics And Machinery - Fluid Properties and Flow Characteristics : Momentum Equation |

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