# Forces (Original)

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Forces (Original)

## 1. Magnetic Force

### 1.1. Examples of magnetic forces in daily life

1.1.1. - A magnetic catch for the door of a cabinet keeps the door shut tight.

1.1.2. - The needle of a compass is a small magnet. A compass is used to give directions.

1.1.3. - The crane uses a powerful magnet to lift iron and steel objects.

## 3. What is a Force?

### 3.1. It can be used to

3.1.1. - Change the shape or size of an object or to make an object move. (given that the amount of force put in is enough)

3.1.2. - Start an object moving or stop a moving object.

3.1.3. - Change the direction of a moving object.

3.1.4. - Change the speed of a moving object, either by increasing its speed or slowing it down.

## 5. Frictional Force

### 5.2. We cannot live without friction. Why?

5.2.1. [Nails]: Friction holds a nail in a wall.

5.2.2. [Bicycle]: Friction between the wheel and the brakes slows down the bicycle.

5.2.3. [Moving]: Friction between our feet and the ground gives us the grip needed to walk and run.

### 5.5. Friction can also be a problem.

5.5.1. Sometimes it can be a nuisance because it makes movement more difficult and wears away materials quickly.

5.5.1.1. Friction between the tyres and the road can wear out the rubber on the tyres.

5.5.1.1.1. It is dangerous on a wet road because the friction between the road and the tyre would then be very little, thus not being able to brake the car as quickly.

5.5.1.2. Friction between the air and the cyclist slows down the speed of the cyclist.

### 5.6. Ways of reducing friction

5.6.1. Use of lubricant (such as crude oil) to make the surface smoother

5.6.2. Use of ball bearings

5.6.3. Make the object more streamlined