Simple Machine – JSS3 Basic Science Lesson Note (Third Term)

Definition of Simple Machine

A machine is a tool or device that makes work easier. It is defined as a tool that uses force applied (effort) at one point to overcome another resisting force (effort) at another point. Examples of machines include a plier, the human arm, a gear, a pulley, etc.

Types of Machine

There are six types of simple machines. They are;

1. Lever
2. Wheel and axle
3. Pulley
4. Wedge
5. Inclined plane crew
6. Screw

Lever

A lever is a simple machine built on the principle of a stiff bar resting on a pivot or fulcrum with a load placed at one end and effort applied on the other end.

There are three parts of the lever;

1. Load: This is the point of the resisting force.
2. Effort: This is the point where force is applied.
3. Fulcrum: This is the turning point of the lever.

Types of Lever

There are three classes or orders of lever. They are;

• First Order Lever: In this lever, the fulcrum is between the load and effort (LFE). Examples include scissors and claw hammers.
• Second Order Lever: In this lever, the load (L) is between the effort (E) and the fulcrum (F) (FLE). Examples of this include; wheelbarrows, nutcrackers, bottle openers,s etc.
• Third Order Lever: In this lever, the effort is between load and effort. (FEL). Examples of this include; the forearm.

Wheel and Axle

This simple machine is used to lift heavy loads from depth. It consists of a large wheel on a small axle that turns on the same axis. Examples of wheels and axles include bicycles, fans, wagons, etc.

Uses

It is used to draw out heavy loads from depths

It is used to create the turning effects in bicycle

Pulley

A machine consisting of a wheel over which a pulled rope or chain runs to change the direction of the pull used for lifting a load. Combinations of two or more pulleys working together reduce the force needed to lift a load.

Uses

It is used to lift and move load in cranes

It is also used in lifts (elevators)

Wedge

A wedge is a triangular-shaped tool and is a portable inclined plane. It can be used to separate two objects or portions of an object, lift an object, or hold an object in place.

Use

It is used to split objects open, especially wood.

Screw

A screw is a type of fastener characterized by a helical ridge known as a thread. Most screws rotate in a clockwise manner but few rotate in an anticlockwise manner.

Use

It allows drilling into hard surfaces

Inclined plane

An inclined plane is a flat supporting surface tilted at an angle, with one end higher than the other, used as an aid for raising or lowering a load. The inclined plane is often used to lift a load over a vertical obstacle.