## Engineering Mechanics Basic Interview Questions and Answers:

1. Define Engineering Mechanics.

Ans. It is defined as the branch of physical science which deals with the behavior of a body at rest or motion under the action of forces.

2. What is the difference between Engineering and Science?

Ans.

Engineering is an art of utilization of the established facts, laws and principles to create certain desired phenomena.

Science is concerned with a systematic understanding and gathering of the facts, laws and principles governing natural phenomena.

3. What are the classification of Engineering Mechanics?

Ans.

• Mechanics of Rigid bodies
• Mechanics of deformable bodies
• Mechanics of solids

4. Define Statics.

Ans. It is the branch of science, which deals with the study of a body at rest under the action of forces.

5. Define Dynamics.

Ans. It is the branch of science which deals with the study of motion of bodies, and the effect of forces acting on them.

6. Define Kinetics

Ans. It is the branch of dynamics which deals with the motion of bodies, problems referring to the forces causing the motion of the body.

7. Define Kinematics.

Ans. It is the branch of dynamics which deals with the motion of bodies problems without referring to the forces causing the motion of the body.

8. Define Fluid Mechanics.

Ans. It is the branch of science which deals with the behavior of fluids, subjected to the action of forces in the state of rest or motion.

9. Distinguish between Particle and Rigid body.

Ans.

A body of negligible dimension is called a Particle.
A large number or particles which occupy fixed positions with respect to each other before and after applying a load is called Rigid body.

10. Distinguish between Mass and Weight.

Ans.

The quantity of matter contained in a body is called Mass.

The force with which a body is attracted towards the center of earth is called weight. W = mg

11. Distinguish between Weight and Weight Density.

Ans.

Weight is a measure of quantity of matter by considering the gravitational force.

Weight Density is the ratio of weight to the volume.

12. Define Unit.

Ans. The accepted standard which is used for comparison of a given physical quantity is known as Unit.

13. What are the different kinds of units?

Ans. MKS, CGS, FPS, SI

14. Distinguish between Units and Dimensions.

Ans.Â

The accepted standard which is used for comparison of a given physical quantity is known as Unit.

Dimension is a formula in which the given physical quantity is expressed in terms of the fundamental quantities raised to suitable powers.

15. Distinguish between Basic units and Derived units:

Ans.

The units in which the fundamental quantities are measured are called Basic units.

The units of derived physical quantities in terms of the fundamental units are called derived units.

16. State the basic laws of Mechanics.

Ans.

• Newton’s first law
• Newton’s second law
• Newton’s third law
• Law of transmissibility of forces
• Parallelogram law of forces

17. State the Newton’s laws of motion.

Ans.

Newton’s first law: Every body continues in its of rest, or of uniform motion in a straight line, unless it is compelled to change that state by external forces.

Newton’s second law: The acceleration of a particle will be proportional to the force and will be in the direction of the force.

Newton’s third law: To every action there is an equal and opposite reaction.

18. State the Newton’s law of Gravitation.

Ans. It States that two particles of mass m1Â and m2Â are mutually attracted with equal and opposite forces.

F = Gm1m2/R2

Where,

• G – acceleration due to gravity
• R – Distance between two particles

19. State the principle of Transmissibility of forces.

Ans. The state of rest or of motion of a rigid body is unaltered if a force acting on the body is replaced by another force of the same magnitude and direction but acting anywhere on the body along the line of action of the replaced force.

20. What are the different types of vectors?

Ans.

• Free vector
• Sliding vector
• Bound (or) Fixed vector
• Unit vector
• Negative vector
• Zero vector (or) Null vector

21. State the difference between Scalar and vector quantities with examples.

Ans.

The quantity which has only magnitude is called Scalar quantity.
Ex: length, area, volume

Vector quantity has both magnitude and direction.
Ex: force, velocity, acceleration

22. Define Vector.

Ans. A quantity which is completely specified by its magnitude as well as direction is called a Vector.
Ex: weight, displacement, velocity

23. What are the characteristics of Vectors?

Ans.

• Magnitude
• Direction
• Point of application
• Line of action

24. What are Free vector?

Ans. Vector which freely moves in space is called Free vectors. Ex: couple

25. What are Sliding vectors?

Ans. Vectors which may be moved, or slide along their line of action is called sliding vectors. Ex: forces acting rigid bodies.

26. What are Fixed vectors?

Ans. A vector used to represent a force acting on a given particle has a well- defined point of application namely, the particle itself. Such a vector is called Fixed vector.

27. Define Unit vector.

Ans. A vector of unit magnitude is called as Unit vector. The unit vector of a force is obtained by dividing the given force by its magnitude.

28. Define Null vector.

Ans. A vector of zero magnitude (which can have no direction associated with it) is called a Null or Zero vector.

29. Define Moment of a force.

Ans. The moment of a force about a point is defined as the turning effect of a force about that point.

30. What are the two important laws used in vector addition and substraction?

Ans.

31. Define line of action of a force.

Ans. An infinite straight line along which the force acts is called line of action of a force.

32. Define Coplanar forces.

Ans. If the forces are contained in the same plane, then they are called Coplanar forces.

33. Define like parallel forces.

Ans. The parallel force which acts in same direction are called like parallel forces.

34. Define Equal vector.

Ans. If two vectors whose magnitude and direction are same, then they are called equal vectors.

35. Define the term ‘Time’ in mechanics.

Ans. Time refers to the sequence of events. It is related to the concepts of before. after and simultaneous occurrence of two or more events.

36. Mention the necessity of units of measurement.

Ans. It is used for comparison of a given physical quantity.

37. Define ‘Newton’.

Ans. It is defined as the force which gives an acceleration of 1 m/s2 to a mass of 1 kg.

38. What is the principle of homogenuity of dimensions?

Ans. The dimensions of all terms on the two sides of an equation must be the same.

39. Mention the uses of dimensional formula.

Ans.

• To check the correctness of a given equation
• To derive equations for physical quantities involved in the problem.

40. Define Metre.

Ans. The metre is the basic unit of length. It is the distance light travels in a vacuum in (1/299792458)th of a second.

41. Define Kilogram (kg).

Ans. It is the basic unit of mass. It is the mass of an international prototype in the form of a Platinum-Iridium cylinder kept at Svres in France.

42. Define Second (s).

Ans. It is the basic unit of time. It is the length of time taken for 9192631770 periods of vibration of the Caesium-133 atom to occur.