# Simple Machines – Class 5

Machines makes our work easier. There are many tasks which need a lot of time and effort to do them. There are also many tasks that we cannot do ourselves. To do such tasks we use machines. Machines makes our work a lot easier and takes less time.

### What are Simple Machine?

Machines can be simple or complex. Simple machines a very few parts. They are the most basic of the machines that are used by us daily to make our work easier. A complex machine consists of two or more simple machines.

### Types of Simple Machines

Some examples of simple machines are lever, pulley, wedge, screw, wheel and axle, and inclined plane.

### Lever

A lever is like a see saw. It is used to lift a heavy load on one end when effort (force) is applied on the other end. A lever consists of the following parts – Fulcrum, Load and Effort.

Fulcrum: A lever consists of a rigid bar and the fixed point around which the simple machine is free to turn is called the fulcrum.

Load: The heavy object on which the work is to be done is called the load.

Effort: The force that is applied to lift a load is called effort.

### Types of Lever

There are mainly 3 types of levers depending on the position of the fulcrum, load and effort.

Class – I Lever: It is a lever in which the fulcrum is located between the load and the effort.
Example: a see-saw, a pair of scissors and a crowbar.

Class – II Lever: It is a lever in which the load is located between the fulcrum and the effort.
Example: a wheelbarrow, a nutcracker and a bottle opener.

Class – III Lever: It is a lever in which the effort is located between the fulcrum and the load.
Example: a fishing rod, a tweezers.

### What is a Pulley?

A pulley is a simple machine which is used to lift heavy objects. It consists of a wheel that has a grooved track for the rope, chain or belt to move through it.

### Types of Pulley

There are two types of pulleys:
Fixed pulley: A fixed pulley has a fixed axle and it is fixed firmly attached to one spot. In a pulley, an effort is applied in one direction and a load moves in another direction. Fixed pulley is used to draw a bucket of water from a well by pulling the rope.
Movable pulley: A movable pulley has a free or movable axle. It is used along with a fixed pulley. A crane uses both fixed and movable pulleys to lift heavy loads.

### What is a Wedge?

A wedge is a simple machine that has a long triangular shape. It is actually made up of two inclined planes joined together. It has one broad or blunt end and one sharp end. It is often made of metal, wood, stone or plastic. Examples of wedge are an axe, a knife and a saw.

### What is a Screw?

A screw is a modified inclined plane wrapped around a cylinder. It is a nail-shaped object with a spiral ridges called thread and a slotted head. Since screw is really an inclined plane that goes round and round, it holds things together more firmly than a nail. Screws are used to fix light bulbs and to lift cars and trucks.

### What is Wheel and Axle?

A wheel and axle is a simple machine consisting of a wheel rigidly attached to a rod called axle. When the wheel is rotated, the axle also rotates. A screw driver, steering wheel of a car and door knob are some examples of wheel and axle.

### What is an Inclined Plane?

An inclined plane is a simple machine in which a sloping or tilted surface is used to lift heavy loads with less efforts. It is flat surface raised at one end. The lesser the inclination of the plane, the lesser the effort needed to lift up the load. Ramps in hospitals or offices, hill slope are some examples of inclined plane.

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