# Machine Study Guide

INTRODUCTION

Have you ever tried opening a paint can lid using your fingernails only to discover that it’s impossible? However, it becomes effortless when you wedge a screwdriver tip between the lid and the rim of the can to pry it open. What happened there? How were you able to generate the force needed to open the lid the second time but not the first? There’s a simple mechanism of physics at play there that often goes unappreciated. Let’s take a look into a number of such machines and mechanisms that make our life easier!

## WHAT ARE MACHINES?

• Machines are mechanical devices that receive an input in the form of work and transfer that energy to generate an output work.
• These devices can change the magnitude or direction of the applied force to perform work.
• Prying open the lid of the paint can use a simple mechanism called a Lever which multiplies force.
• There are a number of such machines which makes it possible for us to apply the right force at the right place without too much effort.

## SIMPLE MACHINE

A simple machine is a device that can change the magnitude or the direction of the applied force. Here are some the examples of simple machines:

### LEVER

A lever is a simple machine that multiplies force. It consists of a straight bar balanced on a pivot point called a fulcrum. When you apply a force on the effort arm of the lever, it generates a higher force on the resistance arm. Opening the lid of a paint can use the principle of the lever to magnify the force.

### WHEEL AND AXLE

The wheel and axle reduce the effort needed to carry large weights over long distances by reducing friction. They were also an early invention used to draw water out of wells. The wheel made it easier to pull huge weights up, such as drawing buckets of water.

### PULLEY

• The pulley is a variant of the wheel and axle designed specifically for exerting small effort to lift heavy loads.
• There are a number of pulley types that makes lifting and moving tasks easier.

### INCLINED PLANE

• Inclined planes are used to reduce the effort when a heavyweight has to be hoisted up.
• Instead of lifting it straight up by applying maximum force, an inclined plane is used to drag the weight with lesser effort.

### SCREW

• The screw is one of the most used of the six simple machines.
• When you look closely, it is basically an inclined plane wrapped around a shaft! A car jack is an excellent example of how it works.
• Since it is impossible for a person to lift a car, they can turn a lever and raise it up slowly over the inclined plane of a screw jack.

### WEDGE

• A wedge is a simple device with an inclined plane at the tip used to exert force between two objects to split them apart.
• With each blow, the wedge makes its way deeper, driving the two objects apart.

## SUMMARY

• Machines can take input work and perform output work.
• The energy at the input is the same as the energy at the output.
• Simple machines can change the direction or magnitude of the applied force.

## FAQs

Q. What is a simple machine?

Going by the definition of simple machines, a simple machine is a mechanical device that can change the magnitude or direction of applied force.

Q. What are the names of simple machines?

Simple machines include lever, wheel and axle, pulley, inclined plane, screw, and wedge.

Q. What are the uses of simple machines in our daily life?

The importance and need for simple machines are understood when we have to perform simple tasks such as opening a tight lid using a lever, opening bottle caps using a bottle opener, and extracting lemon juice using a lemon squeezer.

We hope you enjoyed studying this lesson and learned something cool about Machines! Join our Discord community to get any questions you may have answered and to engage with other students just like you! Don’t forget to download our App to experience our fun VR classrooms – we promise, it makes studying much more fun! 😎

## REFERENCES

1. Machine: https://flexbooks.ck12.org/cbook/ck-12-physics-flexbook-2.0/section/7.2/primary/lesson/simple-machines-phys/ Accessed 11th April 2022.
2. Six Simple Machines: https://byjus.com/physics/simple-machines/ Accessed 11th April 2022.
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