Introduction to Simple Machines - JSS2 Basic technology Lesson Note

Simple machines are basic mechanical devices that change the direction or magnitude of a force. They make work easier by allowing us to exert less force over a greater distance. The six classic types of simple machines are levers, pulleys, gears, wheels and axles, inclined planes, and screws.

Levers: A lever is a rigid bar that pivots around a fixed point called the fulcrum. By applying force at one point on the lever, a greater force can be exerted at another point. Levers are classified into three types based on the relative positions of the fulcrum, effort, and load:

1. First-Class Lever: The fulcrum is between the effort and the load (e.g., seesaw, crowbar).
2. Second-Class Lever: The load is between the fulcrum and the effort (e.g., wheelbarrow, nutcracker).
3. Third-Class Lever: The effort is between the fulcrum and the load (e.g., tweezers, fishing rod).

Pulleys: A pulley consists of a wheel with a grooved rim and a rope or cable that runs along the groove. Pulleys are used to lift heavy loads with less effort. There are two main types:

1. Fixed Pulley: Changes the direction of the force applied (e.g., flagpole).
2. Movable Pulley: Reduces the amount of input force needed to lift a load (e.g., construction cranes).

Gears: Gears are wheels with teeth that interlock to transmit motion and force from one part of a machine to another. They can change the direction of movement, increase speed, or increase force. Gears are commonly found in bicycles, clocks, and car transmissions.