FEA Interview Questions in Engineering Mechanics:

1. What is mechanics and its classifications?

• Mechanics is a branch of the physical science that is concerned with the state of rest or motion of bodies that are subjected to the action of forces.
• In general, this mechanics can be classified as below:

2. What is rigid body?

A rigid body can be considered as a combination of a large number of particles in which all the particles remain at a fixed distance from one another, both before and after applying a load.(No deformation)

In most cases the actual deformations occurring in structures, machines, mechanisms, and the like are relatively small, and the rigid-body assumption is suitable for analysis.

3. State: Newton’s Three Laws of Motion.

First law:
• If a particle is at rest (or moving with constant velocity in a straight line), it will remain at rest (or continue to move with constant velocity in a straight line) unless acted upon by a force.

Second law:

• A particle acted upon by a force will accelerate in the direction of the force. The magnitude of the acceleration (a) is proportional to the magnitude of the force(F) and inversely proportional to the mass (m) of the particle.

F=ma Where F - Applied force M - Mass of the particle A- Acceleration of the particle

Third Law:

• For every action, there is an equal and opposite reaction; that is, the forces of interaction between two particles are equal in magnitude and oppositely directed along the same line of action.

4. What is equilibrium of a particle or system?

• A particle is said to be in equilibrium if it remains at rest if originally at rest, or has a constant velocity if originally in motion
• Static equilibrium” is used to describe an object at rest.
• To maintain equilibrium, it is necessary to satisfy Newton’s first law of motion, which requires the resultant force acting on a particle to be equal to zero.
• This condition may be stated mathematically as
  
  ∑F = 0
  

5. What is the difference between scalar and Vector?

A scalar is a quantity that has magnitude only.	A vector is a quantity that possesses magnitude and direction and obeys the parallelogram law.
E.x. Length, Mass, Pressure	E.x. Weight, Force

6. What is free body diagram?

• A free body diagram is a graphical illustration of an isolated section or member of a part or a system.
• Used visualize the applied forces and moments and resulting, reactions, on a body in steady state condition (not in accelerated condition).
• Free body diagram must satisfy the equations of static equilibrium in the principles of statics.

7. What is moment?

• When a forces are applied to the body, it rotate about a Center point which is not in the line of action of force is called moment.
• This tendency is called “torque”.

Moment=force Χ distance which is perpendicular the direction of force

M= Fd

Where, M- Moment F- Force d- Distance which is perpendicular the direction of force

8. What is couple?

• Two parallel, noncollinear forces that are equal in magnitude act in opposite direction is called couple .
• Its effect is to produce pure rotation or tendency for a rotation in a specified direction.
• Resultant force value of a couple is zero.

9. What is Friction?

When two surfaces are in contact with each other one surface tend to move with respect to the other, tangential force will be developed at the contact surface in the opposite direction of motion is called friction.

10. Friction is advantage or disadvantage? Justify?

Friction force has both advantage and disadvantage.

Advantage:

• Friction between floor and feet, Enable us to walk on floor(less friction makes us to slide)
• Friction between road and Vehicle, help us to ride vehicles on road.
• Transmission of power using belt…and the like.

Disadvantage:

• Wear between components in a system
• Tear
• Loss of power, Loss of energy…etc.