21 Short Answer Type Viva Questions on Kinematic Mechanisms

21 Short Answer Type Viva Questions on Kinematic Mechanisms

1. Define Machine.

Answer:

A machine is a device which receives energy in some available form and utilizes it to some particular type of work.

2. Define Theory of Machines.

Answer:

Theory of Machines deals with the study of relative motion between the various parts of a machine and the forces which act on them.

3. Define Kinematics of Machines.

Answer:

It deals with the relative motion between the parts neglecting the forces which are responsible for producing these motions.

4. Define Dynamics of Machines.

Answer:

It deals with the study of forces acting on the parts of a machines.

5. Define statics.

Answer:

It deals with the study of forces which act on the various parts of machines provided the parts must be in the position of rest.

6. Define kinetics.

Answer:

It deals with the inertia forces due to mass mass and motion considerations.

7. Define Rigid Body.

Answer:

It may be defined as a body which can retain its shape and size, when subjected to some external forces. In actual practice, no body is perfectly rigid, but for simplicity we can take the solid bodies as rigid bodies.

8. Define Resistant bodies.

Answer:

A resistant body is that which does not suffer appreciable distortion or change in physical form by forces acting on it. Some flexible bodies like belts, ropes and chains etc. may be treated as resistant bodies.

9. Define Kinematic Link.

Answer:

Each part of machine which moves relative to other is called kinematic link or element. A link or an element may consist of a number of parts connected in such a way that they form one unit and have no relative motion with each other. For example, piston, piston rod and cross-head of steam engine constitute one unit and will be taken as one link or element.

10. Name different types of links.

Answer:

  1. Rigid link
  2. Flexible link
  3. Fluid link

11. Define Rigid link

Answer:

A rigid link is one which does not undergo any deformation while transmitting motion. In actual practice, no link is perfectly rigid, but as deformation is negligible, they can be considered as rigid.

12. Define Flexible Link.

Answer:

A flexible link is that which, while transmitting motion, is partly deformed in such a manner that transmission of motion is not affected. Such a link transmits motion in one direction only (push or pull). Examples are belts, ropes, springs, chains etc.

13. Define Fluid Link.

Answer:

It is formed by having fluid in  a receptacle and motion is transmitted through the fluid b pressure or compression. Examples are hydraulic jacks, Hydraulic presses etc.

14. Define Structure.

Answer:

It is an assembly of a number of resistant bodies having no relative motion between them and meant to take up loads having straining action. Examples are Roof trusses, bridges, buildings etc.

15. Define frame.

Answer:

It is a structure which supports the moving parts of a machine.

16. Define Kinematic Pair.

Answer:

A pair is formed when there is a contact between the two links of a machine and there is relative motion between the two links. The relative motion between the two links must be completely or successfully constrained to make a required pair.

17. Define completely constrained motion.

Answer:

When the motion between a pair is in a definite direction irrespective of the direction of the applied force, such motion is known as completely constrained motion. For example,  the motion of piston in a cylinder of an internal combustion engine takes place in a definite direction and is therefore a completely constrained motion.

18. Define incompletely constrained motion.

Answer:

When the motion between a pair takes place is more than one direction, such motion is known as incompletely constrained motion. Example a circular bar moving in a circular hole.

19. Define partially constrained motion.

Answer:

When the constrained motion between a pair is not completed by itself, but by some other means, such motion is known as partially of successfully constrained motion. Example, the shaft in the footstep bearing.

20. Define Lower Pair.

Answer:

The kinematic pair which has surface contact between its links while transmitting motion is known as lower pair. For example, a shaft revolving in a bearing, piston reciprocating in the cylinder of an IC engine.

21. Define Higher Pair.

Answer:

The kinematic pair which has point or line contact between its links while transmitting motion is known as higher pair. For example cam and follower pair, ball and roller bearings.

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