Kinematics is the study of motion, without considering the forces which produce that motion. Kinematics of machines deals with the study of relative motion of machine parts. It involves the study of position, displacement, velocity and acceleration of machine parts.
What Is A Machine?
A machine is a mechanism or collection of mechanisms, formed and connected so that they move with definite relative motions and transmit force from the source of power for the resistance to be overcome. Though all machines are mechanisms, all mechanisms are not machines. A machine has two functions: transmitting definite relative motion and transmitting force. These functions require strength and rigidity to transmit the forces.
Examples of machines include:
- Drilling machine
- Lathe machine slotting machine
- Molecular machines
- Computers
- Screw jack
- Food blender
- Robot
- Amusement park ride
- Automobile transmission etc.
What You Need To Know About Machine
- Since a machine comprises of mechanisms, the parts of a machine moves relative to one another.
- Machines serve to modify and transmit mechanical work.
- Links of a machine may transmit both power and motion e.g lathe and shaper.
- The machine transforms the available energy into some useful work.
- Machines can have one or two mechanisms.
- A machine may consist of flexible links like belts and chains which undergo partial deformation when transmitting power and motion.
- Examples of machines include: Drilling machine, Lathe machine, slotting machine and screw jack etc.
What Is A Structure?
A structure is an assembly of resistant bodies (referred to as members) such that these bodies don’t have any relative motion between them. A structure is meant for carrying loads, it consists of only resistant bodies that undergo negligible deformation while bearing the load.
Examples of structures include:
- Building
- Bridge
- Trusses
- Machine frames
- Railway bridge etc.
The degree of freedom of a structure is zero. A structure with a negative degree of freedom is referred to as a preloaded structure.
What You Need To Know About Structure
- The members of a structure do not move relative to one another.
- Structures serve to modify and transmit forces.
- Links carry loads having straining action e.g bridge, roof truss etc.
- In a structure, no energy is transformed into useful work. The purpose of a structure is to bear the load for which it is designed.
- Structures do not have mechanism.
- A structure consists of only resistant bodies that undergo negligible deformation while bearing the load.
- Examples of structures include: building, bridge, trusses, machine frames etc.
Difference Between Machine And Structure In Tabular Form
| BASIS OF COMPARISON | MACHINE | STRUCTURE |
| Movement | Parts of a machine moves relative to one another. | The members of a structure do not move relative to one another. |
| Purpose | Machines serve to modify and transmit mechanical work. | Structures serve to modify and transmit forces. |
| Links | Links of a machine may transmit both power and motion e.g lathe and shaper. | Links carry loads having straining action e.g bridge, roof truss etc. |
| Working | The machine transforms the available energy into some useful work. | In a structure, no energy is transformed into useful work. |
| Mechanism | Machines can have one or two mechanism. | Structures do not have mechanism. |
| Examples | Drilling machine, Lathe machine, slotting machine and screw jack. | Building, bridge, trusses, machine frames etc. |