# Fluid Mechanics Questions and Answers – Specific Force

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This set of Fluid Mechanics Multiple Choice Questions & Answers (MCQs) focuses on “Specific Force”.

1. Which among the following provides the third principle in fluid mechanics?
a) Conservation of mass
b) Conservation of linear momentum
c) Conservation of Heat
d) Conservation of volume

Explanation: In fluid mechanics, the third principle is given by the conservation of linear momentum. It is in addition to the continuity of mass and conservation of energy. They are mostly seen in channel flow problems.

2. Momentum principle states that all the forces acting in the system result in a change in momentum.
a) True
b) False

Explanation: Momentum principle states that all the forces acting in the system result a change in momentum. It is in addition to the continuity of mass and conservation of energy. Thus, the correct option is “true”.

3. Which among the following is not a force that acts in the downstream of the fluid flow?
a) Pressure
b) Weight
c) Friction
d) Gravity

Explanation: Frictional force is a force that does not act in the downstream of the fluid flow. Friction acts in the upstream direction, as friction always opposes the flow of fluid through a stream developing a viscous flow.
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4. Which among the following is present in pipe flow?
a) Viscous force
b) Inertial force
c) Gravity force
d) Pressure force

Explanation: Pressure is a force that is applied perpendicular to the surface of an object over a unit area of force. It is defined as the product of pressure intensity and cross-sectional area of the flowing fluid. Pressure force is present in the case of pipe flow.

5. What is momentum?
a) Mass * acceleration
b) Mass * Volume
c) Mass flow rate * velocity
d) Mass flow rate* density

Explanation: Momentum is an expression that is made up of two main functions. These two terms play a significance role in determining the function. The two terms are mass flow rate and velocity. Thus, the final formula is mass flow rate * velocity.

6. A force that is needed to bring back the body to its original position is called as?
a) Viscous force
b) Elastic force
c) Gravity force
d) Pressure force

Explanation: Elastic force is the force that brings a body back to its original position. It is defined as the product of elastic stress and the area of the flowing fluid.

7. What is a specific force denoted as?
a) N
b) F
c) M
d) S

Explanation: Specific force is defined as the force that is expressed in terms of its momentum. It is the momentum of flow passing through a channel of cross section per unit time per unit weight and a second is a force per unit weight. This sum is called the specific force.

8. Energy is not conserved throughout the pipe.
a) True
b) False

Explanation: It is not possible when the initial speed is less than the critical speed. There is a transition that is created during the change. Though momentum is conserved throughout the hydraulic jump, energy is not conserved.

9. Specific force is __________ to mass flow rate.
a) Directly proportional
b) Inversely proportional
c) Independent
d) Not proportional

Explanation: Specific force is directly proportional to the mass flow rate. Specific force is defined as the force that is expressed in terms of it momentum. It is the momentum of flow passing through a channel of cross section per unit time per unit weight and a second is the force per unit weight.

10. Specific force is __________ to cross sectional area.
a) Directly proportional
b) Inversely proportional
c) Independent
d) Not proportional

Explanation: Specific force is inversely proportional to the mass flow rate. Specific force is defined as the force that is expressed in terms of it momentum. It is the momentum of flow passing through a channel of cross section per unit time per unit weight and a second is the force per unit weight.

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