# Forces and Pressure

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or sign up with your email address Forces and Pressure ## 1. Forces :D

### 1.1. What is a force? o.O

1.1.1. A force is needed in everything we do

1.1.2. A force is a push or pull

1.1.3. We exert force when we push or pull something. Actions such as lifting, bending, stretching, twisting or squeezing involve pushes and pulls.

### 1.2. What are the types of forces?

1.2.1. Magnetic Force

1.2.1.1. A magnetic Force is exerted by a magnet Examples of magnetic forces in our daily lives: Needle of compass, Door of a cabinet, Crane that lift iron and steel objects

1.2.1.1.1. When like poles of both magnets are facing each other, they will repel(pushing force).

1.2.1.1.2. When unlike poles of both magnets are facing each other, they will attract (pulling force).

1.2.2. Frictional Force

1.2.2.1. Occurs when two objects are in contact

1.2.2.2. Causes a moving object to slow down and stop

1.2.2.3. Produces heat (e.g. rubbing your hands together) Reason: Our hands will exert friction to produce heat.

1.2.2.4. Advantages of Friction

1.2.2.4.1. Friction prevents us from falling or slipping easily

1.2.2.4.2. Friction between our feet and ground gives a better grip needed for any movements.

1.2.2.5. Disadvantages of Friction

1.2.2.5.1. Causes wear and tear and hinders movement

1.2.2.5.2. Friction between the wooden box and the ground makes it hard to be pushed from one end to another.

1.2.2.5.3. Friction causes the tyres of cars to wear out and thus would not have a good grip between the road and the tyres on rainy days. It may cause the car to skid on the road.

1.2.2.6. How to reduce Friction?

1.2.2.6.1. Friction can be reduced by using a smooth surface, ball bearings, rollers, lubricants and streamlining.

1.2.3. Gravitational Force

1.2.3.1. Gravitational force pulls objects towards the Earth.

1.2.3.2. Gravitational force exists between any two objects.

1.2.3.3. It acts towards the center of a mass of an object . For instance, the gravitational force would be towards the center of the Earth.

1.2.3.4. Weight

1.2.3.4.1. The gravitational force on Earth is equal to the force that the Earth exerts on you.

1.2.3.4.2. The weight of an object depends on the force of gravity pulling on that object.

1.2.3.4.3. Thus, the greater the force of gravity pulling onto an object, the heavier the weight of the object.

1.2.3.4.4. Weight can be measured using a spring balance and is measured in newtons (N).

## 2. Calculating Pressure

### 2.1. Unit

2.1.1. Force : N

2.1.2. Area : m square or cm square

2.1.2.1. New node

2.1.2.1.1. New node

2.1.3. Pa(pascal) : N/m square SI unit of pressure : PA

### 2.2. The Equation

2.2.1. Pressure equals to Force divided by Area

## 4. How to Increase pressure or decrease pressure?

### 4.1. Decrease

4.1.1. To reduce pressure, the increase in area is an option. An example is when people or machines move on soft ground or snow,low pressures are need. when a larger surface is in contact with the ground, lower pressure is exerted on the ground, thus people or machines can move withou sinking. other examples are a camel has flat big feet to spread its weight over a large area while another example is the surface area of a ski is large to prevent the skier from sinking into the snow.

### 4.2. Increase

4.2.1. To increase pressure, the area in contact with an object should be smaller and the same amount of force should be used.