Welcome to a world full of Welcome to a world full of machines!machines!

STD 6STD 6thth SUB: science SUB: science

By Usha dherangeBy Usha dherange

Guidance : Dr. Mabel Guidance : Dr. Mabel PimentaPimenta

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 machines3) 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.

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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 driveror 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 MachinesThe 6 Simple Machines

All machines are made up of some of All machines are made up of some of the 6 simple machines. They are:the 6 simple machines. They are:

Wheel and axleWheel and axle PulleyPulley Inclined PlaneInclined Plane WedgeWedge ScrewScrew leverlever

Why do we need simple Why do we need simple machines?machines?

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

The Wheel and AxleThe Wheel and Axle

Two or more wheels Two or more wheels are connected by an are connected by an axle. axle.

The wheel turns with The wheel turns with or around the axle.or around the axle.

This car wheel has a This car wheel has a big axle that it big axle that it rotates around when rotates around when the car moves. the car moves.

Axle

Wheel

Click on the windmill to learn more.

Why do we need wheels?Why do we need wheels?

Wheels help us move heavy objects. Wheels help us move heavy objects. They roll easily.They roll easily. Did you know a doorknob is really Did you know a doorknob is really

two wheels connected by an axle? two wheels connected by an axle? You can’t see the axle because it’s You can’t see the axle because it’s inside the wheels, but it’s there! inside the wheels, but it’s there!

If there wasn’t an axle, the doorknob If there wasn’t an axle, the doorknob wouldn’t turn!wouldn’t turn!

Another kind of wheel is Another kind of wheel is called a gear!called a gear!

A gear is a wheel with teeth. A gear is a wheel with teeth. The teeth fit in between each other The teeth fit in between each other

and turn. and turn. When one gear turns, its teeth push When one gear turns, its teeth push

against the teeth of the other gear against the teeth of the other gear and they both turn. and they both turn.

There are gears on your bike, on a There are gears on your bike, on a can opener and on an egg beater.can opener and on an egg beater.

Pulleys Pulleys

Lifting a bucket full of water Lifting a bucket full of water is a lot of work!is a lot of work!

A pulley is a wheel with a A pulley is a wheel with a rope running over it. The rope running over it. The wheel has a groove, called a wheel has a groove, called a sheave, and it keeps the sheave, and it keeps the rope from slipping off the rope from slipping off the wheel. wheel.

Remember, since there is a Remember, since there is a wheel in a pulley there also wheel in a pulley there also has to be an axle!has to be an axle!

These two men are using a These two men are using a pulley to help them lift their pulley to help them lift their

heavy bucket.heavy bucket.

The Inclined PlaneThe Inclined Plane

It is a slanted surface It is a slanted surface or ramp. or ramp.

It makes moving It makes moving objects easier. objects easier.

Roads are also Roads are also inclined planes. inclined planes. Instead of going Instead of going straight up, like this: straight up, like this: roads go up at small roads go up at small angles, like the angles, like the picture.picture.

The 6 Simple MachinesThe 6 Simple Machines

Lever

PulleyWheel and Axle

WedgeScrew

Inclined Plane

Why do we need simple Why do we need simple machine?machine?

Simple machine

Function of machine

Benefits to mankind

Inclined plane

Pulley

Wheel & axle

Discuss in a group and complete the table