Welcome to a world full of machines! STD 6 th SUB: science By Usha dherange By Usha dherange Guidance : Dr. Mabel Pimenta

Learning outcomes After going through this session learners will be able to, 1) Explain what a machine is and how it makes work easier. 2) Identify the types of simple machines 3) Identify the forces involved in simple machines

. There are machines all around us! Turn to your neighbor and discuss what kinds of machines you saw on your way to school today. ************* Have you ever tried to unscrew a nut, bolt, or screw from something with your bare hands and discovered that it was just too tight to loosen even if you had a good grip? What did you do?

You got the proper tool, such as a screw driver or wrench, and unscrewed it!

The wrench and screw driver are examples of a wheel and axle, where the screw or bolt is the axle and the handle is the wheel. The tool makes the job easier by changing the amount of the force you exert. Axle Wheel

Simple machines are useful because they can make a physical job easier by changing the magnitude or the direction of the force exerted to do work.

The 6 Simple Machines b All b All machines are made up of some of the 6 simple machines. They are: b Wheel b Wheel and axle b Pulley b Inclined b Inclined Plane b Wedge b Screw b lever

Why do we need simple machines? b Work means that we are exerting force and moving something. The 6 simple machines make our work easier. We won’t have to use as much force with our simple machines.

The Wheel and Axle b Two or more wheels are connected by an axle. b The wheel turns with or around the axle. b This car wheel has a big axle that it rotates around when the car moves.

Axle Wheel Click on the windmill to learn more.

Why do we need wheels? b Wheels help us move heavy objects. b They roll easily. b Did you know a doorknob is really two wheels connected by an axle? You can’t see the axle because it’s inside the wheels, but it’s there! b If there wasn’t an axle, the doorknob wouldn’t turn!

Another kind of wheel is called a gear! b A gear is a wheel with teeth. b The teeth fit in between each other and turn. b When one gear turns, its teeth push against the teeth of the other gear and they both turn. b There are gears on your bike, on a can opener and on an egg beater.

Pulleys b Lifting a bucket full of water is a lot of work! b A pulley is a wheel with a rope running over it. The wheel has a groove, called a sheave, and it keeps the rope from slipping off the wheel. b Remember, since there is a wheel in a pulley there also has to be an axle! b These two men are using a pulley to help them lift their heavy bucket.

The Inclined Plane b It is a slanted surface or ramp. b It makes moving objects easier. b Roads are also inclined planes. Instead of going straight up, like this: roads go up at small angles, like the picture.

The 6 Simple Machines Lever Pulley Wheel and Axle Wedge Screw Inclined Plane

Why do we need simple machine?

Simple machine Function of machine Benefits to mankind Inclined plane Pulley Wheel & axle Discuss in a group and complete the table