CARSGears

GearsGears

To be able to:

All Most Some

understand how gears can speed up and slow down a machine

Describe how gears work.

Explain the importance of gears in cars

Why is it easier to hammer in a nail than take it out?

Starter: Think!!!How does the size of a wheel affect the

number of turns???

GearsGearsWheels with teeth or cogs on them are

called gear wheels. The teeth of one wheel fit into the teeth of the other, so that they can

transfer the force from one wheel to the other.

A gear is a device used to change motion. For example, a gear is used on a bicycle or in a car to allow the bicycle or car to speed

up or slow down.

GearsGearsDriving gear

The large gear wheel. It supplies the force to turn the small gear wheel.

Driven gear

The small wheel

Gearing up.Gearing up.

The small wheel will make far more turns for each turn of the large wheel. A propeller attached to the small wheel will therefore

turn quickly.

This is an example of gearing up.

Kitchen hand-beaters, hand drills and bicycles have this arrangement of gears, so that the beaters, drill bits and rear wheel can

spin quickly.

Gearing Down Gearing Down Now suppose a small gear wheel is the driving

gear and is attached to a large wheel.

The large wheel will turn slowly compared to the small driving gear.

This is called gearing down.

Anything attached to the large wheel will turn slowly too.

Rotating displays in exhibitions use this arrangement of gears so that the goods on display

move very slowly.

GearsGears

To be able to:

All Most Some

understand how gears can speed up and slow down a machine

Describe how gears work.

Explain the importance of gears in cars

Why is it easier to hammer in a nail than take it out?

Starter: Think!!!How does the size of a wheel affect the

number of turns???

Gears on a BikeGears on a Bike

How do gears on a bike work?

How would your ride be harder if your gears

were broken??

Thinking Question?

Gears on a BikeGears on a BikeBicycles have a large gear wheel attached to the pedals and a

small gear wheel attached to the rear wheel.

The two gear wheels are connected by a chain.

When you push down on the pedals, the pedals turn and the large gear wheel attached to the pedals turns too.

This gear wheel is the driving gear.

The smaller gear wheel attached to the rear wheel is the driven gear

Gears on a BikeGears on a BikeOn bicycles with gears you can select different sized gear

wheels.

If you are going up a hill, you select the largest rear gear wheel. This is low gear and it means you require less effort to

get you and the bike up the hill.

So a bicycle in low gear gives the rider a force advantage. On level ground, you select the smallest rear gear wheel. This is

high gear and it allows you to cover more distance.

So a bicycle in high gear gives the rider a speed–distance advantage. The bike can reach a higher speed and cover

more distance.

Gears in your Gears in your Car Car What about your car? What about your car?

Is it manual or Is it manual or automatic? What's the automatic? What's the

difference?difference?How many gears does How many gears does

it have? Why? it have? Why?

GearsGears

To be able to:

All Most Some

understand how gears can speed up and slow down a machine

Describe how gears work.

Explain the importance of gears in cars

Why is it easier to hammer in a nail than take it out?

Starter: Think!!!How does the size of a wheel affect the

number of turns???

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