Machines play an important role in our lives. Modern age is the age of machines. Almost all objects surrounding us including soap, pen, paper, cloth, TB, bicycle, motor, car, etc., are made by machines.
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Definition
A machine is a device which makes our work easier, faster and more convenient. It can do more work by applying less force. It helps us to gain force. It is used for transferring force. It can also change the direction of force. It does not help us to gain energy.
Some examples of different kinds of machines are knife, cork opener, spanner, inclined plane, scissors, a screw, a wheel, a pulley and pliers. These are called simple machines.
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In science, broom is considered a simple machine. A small muscular force is applied to the handle of the broom by hand. Broom transfers this force to the floor where the work is done.
Some machines are complex. A bicycle is an example of a complex machine. A complex machine is made up of a large number of simple machines. Complex machines are also called compound machines.
Types of Simple Machines
Various types of simple machines are:
- Lever
- Inclined plane
- Wedge
- Screw
- Wheel-and-axle,
- Pulley
1. Lever
A lever is a simple machine. It consists of a rigid rod, which moves freely about a supporting (or fixer). This fixed point is called the fulcrum. There are two more points on a lever where an effort and a load are applied.
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Example:
Consider the lifting or moving of a very heavy object from the ground. There are two ways to life it. One is to lift it directly with hands. The rigid rod is a lever called crowbar. The crowbar makes the lifting of a heavy object easier. The heavy object lifted is called the load. The force applied to lift the load is called the effort. The support around which the rod moves is called the fulcrum.
2. Inclined Plane
A plane surface that makes an angle with horizontal surface is called an inclined plane. An inclined plane is another simple machine. It is often used to raise heavy objects. There are two ways to load a heavy object on a truck.
Examples
- A winding road to a hill station is like an inclined plane.
- The staircases in buildings are like an inclined plane with steps.
3. Wedge
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A knife, an axe and a chisel act like two inclined planes put together.
4. Screw:
A screw is a simple machine. It has a winding edge called a thread. A screw is a spiral inclined plane. It is like an inclined plane wrapped around a cylinder, say a pencil. If you cut a piece of paper into a long, right angled triangle and then warp it around a pencil, the spiral edge looks like the thread of a screw. The thread of a screw is an inclined plane.
5. Wheel-and-Axle
The wheel-and-axle is another simple machine. It consists of a wheel with a rod attached to it. The rod is called an axle. When we move the wheel the axle rotates.
The steering wheel of an automobile is a good example of the wheel-and-axle. Just a little force on the rim of the steering wheel is enough to change the direction of the front wheels of the car. The same is the case with the handle of a bicycle. The screwdriver, egg-beater and the brace-and-bit are other common examples of wheel-and-axle.
6. Pulley
It is a simple machine consisting of a while with a groove which bolds a rope. It is used to change the direction of force. It is used to lift heavy loads or to draw water from the wall.
A pulley consists of a circular disc made of wood or metal and it rotates about an axle passing through its centre. While using a pulley, the load is attached to one end of the rope passing over the pulley and the effort is applied at the other end of the rope.
Builders often use a pulley to lift bricks and cement bags to the top of the building. Pulleys are also used in lifts and in railways to operate signals. Traffic police employ crane to lift cars from no parking sites on roads.
Maintenance of Machines
- Iron parts of machines get rusted. Outer parts of machines should be pained to avoid rusting.
- Moving parts of machines should be lubricated regularly with grease and oil; otherwise they will wear out faster.
- Machines should be protected from dirt and dust which also cause wear and tear. Computers especially must be placed in dust-proof and temperature-mandated room.
- Proper maintenance and care make machines last longer and give us better service.