Lesson 3: Classification of Simple Machines

Lesson 3 Objective

At the end of this section, you should be able to:

list type of simple machines;
categorize simple machines at home and workplace according to their
type;
identify the six types of simple machines.

Brainstorming Question

In the previous section, you have observed different simple machines at home and work place. Can you classify these simple
machines in their types?

key terms and concepts

A simple machine is:

A device that requires only a single force to do mechanical work;
A device that uses a single effort to do a mechanical work against a single load force.

Classification of Simple Machines

Many people often think of machines as complex devices like cars, elevators, or computers. However, some machines are as simple as a hammer, shovel, or ramp. A simple machine is a tool that does work with only one movement. When several simple machines are combined, they form a compound machine, like a bicycle or wire cutter. For example, wire cutters combine two levers and two wedges, while bicycles include wheels and axles, levers, screws, and pulleys. Cars and other vehicles are combinations of many machines.

Simple machines are categorized into two main

1. Inclined Planes

Ramp/Inclined Plane: A flat surface tilted at an angle, used to raise or lower objects with less effort (e.g., a loading ramp).

Wedge: A device that is thick at one end and tapers to a thin edge, used for splitting or cutting (e.g., an axe).

Screw: An inclined plane wrapped around a cylinder, used to hold objects together or lift materials (e.g., a jar lid).

2. Levers

Lever: A rigid bar that pivots around a fixed point (fulcrum) to move a load with less effort. Levers are divided into three classes:
- First-Class Lever: The fulcrum is between the effort and the load (e.g., a seesaw).
- Second-Class Lever: The load is between the fulcrum and the effort (e.g., a wheelbarrow).
- Third-Class Lever: The effort is between the fulcrum and the load (e.g., a fishing rod).

Here is the diagram of the three levels of lever.