Simple Machines - Class 4 Notes & Olympiad Questions

Simple Machines

Simple machines are special tools that are easy to understand and use. They make work simpler, easier, and faster by using a basic and straightforward idea. These machines help us save time, energy, and effort when we're doing tasks.

Different Kinds of Simple Machines

1. Lever

a) A lever is like a long bar that helps us move heavy objects more easily.
b) It can turn around a fixed point called the fulcrum.
c) When we push or pull on one end of the lever, it's called the effort. The heavy object we want to move or lift is called the load.

There are three types of levers:

-> First-class lever: In this lever, the load and effort are on different sides of the fulcrum. Examples include scissors, a see-saw, and a balance scale.

-> Second-class lever: In this lever, the fulcrum and effort are on different sides of the load. Examples include a nutcracker, a bottle opener, door hinges, and a wheelbarrow.

-> Third-class lever: In this lever, the effort is between the load and the fulcrum. Examples include forceps, a fishing rod, ice tongs, and a broom with a handle.

2. Pulley

a) A pulley is like a wheel with a rope around it.
b) It helps us lift or lower things easily by pulling the rope.
c) Examples: drawing water from a well, raising a flag on a flagpole.

3. Inclined Plane

a) An inclined plane is like a flat surface that is slanted.
b) It helps us move heavy objects up or down with less force.
c) Examples: ladder, slide in a playground, stairs.

4. Wheel and Axle

a) The wheel and axle are two cylinders that turn together around a point.
b) It helps us lift heavy things or make them move smoothly.
c) Example: lifting heavy loads using a pulley system.

5. Wedge

a) A wedge is like a sharp tool with a slanted edge.
b) It helps us split or separate things like blocks of wood.
c) Examples: axe, knife, chisel.

6. Screw

a) A screw is like an inclined plane wrapped around a rod or cylinder.
b) It helps us hold things together tightly or move them up and down.
c) Example: screwing in a lightbulb or turning a screw with a screwdriver.

Difference between Wedge and Inclined Plane