You will know about Simple Machines.

Simple machines make our work faster and easier. For example, scissors make it easier to cut things, a screw helps to join or hold wood blocks together, and so on. Machines usually involve movement. All the machines we use in our daily life are combinations of simple machines.

Simple machines are tools that make our work easier by applying force. This force is applied at a particular point. A knife is an example of the simplest machine used by us. The main simple machines which are the basis of all other machines are lever, inclined plane, wedge, wheel and axle, pulley, and screw.

A lever is a simple machine that can be used to lift objects. The lever is a bar that is free to move about a fixed point called a fulcrum. It can increase the force applied by us, like a long bar moving a boulder, or decrease force for delicate tasks, like tweezers used in surgery.

• Load: The weight on which force is applied.
• Fulcrum: The point on which a lever turns or is supported.
• Effort: The push or pull that moves the lever.

When the fulcrum is between the load and the effort, it is called a first-class lever.

A second-class lever has the load between the fulcrum and the effort. Examples: nutcracker, bottle opener, wheelbarrow.

In a third-class lever, the effort is between the fulcrum and load. Examples: stapler, forceps, fishing rods, ice tongs.

An inclined plane is a simple machine used to move objects to a higher place. Examples: ramp, slide, roads going up a hill.

The wedge works on the principle of an inclined plane. The wedge has two inclined surfaces joined together. Examples: axe, knife, razor.

The wheel and axle is a simple machine with a wheel attached to an axle. It helps reduce the effort needed to move or turn objects. Examples: sewing machine, cycle, grinding machines.

A pulley is a simple machine used to lift heavy loads or move objects to hard-to-reach places. Examples: flagpole, clothesline, curtain string.

A screw looks like a nail with grooves. It has a winding edge called a thread and is used to join or hold objects securely. Examples: screwjack, revolving stools, light bulb base.

To make a model of a screw: Take a piece of paper, cut a right triangle from it to form an inclined plane, and wrap it around a nail. The colored inclined edge forms the structure of a screw.

• Machines: Devices that make our work easier.
• Simple machines: Machines having a few parts.
• Ramp: A slope that assists movement, such as in buildings.
• Thread: The raised line on a screw that allows it to be fixed by twisting.

Interactive True/False Quiz