Definition of pressure 

The definition of pressure given here is according to physics because pressure can mean different things depending on the context or what you are talking about.

Pressure depends on the force applied and the area where the force is applied.

The formula to get the pressure is:

Pressure =
F / A

F stands for force and A stands for area.

More precisely, pressure is the ratio of the force to the area where the force is applied.

F is measured in newtons and A is measured in square meter.

Another way to express newtons per square meter is pascals (Pa).

1 Newton per 1 square meter is equal to 1 pascal.

Difference between force and pressure

Let's say your weight is 980 newtons. Lie down flat in your bed.  

The force exerted on the bed is 980 newtons

If you now stand up in your bed, your weight is still 980 newtons.

However, you may notice that this time the mattress is sinking.

Your weight has not changed. However, because your weight is being applied to a smaller area, it is causing more pressure on the mattress.

Another way to express the definition of pressure

                        Pressure is the force per unit area.

Let's say you want to calculate the pressure you exert on your bed when you lie down or when you stand on it.

First, let's find the pressure when you lie down. We will need to approximate the area that you cover when you lie down.

It not a perfect science, but here is how we may approximate the area covered by your body.

First, draw a rectangle around yourself as shown below in red.

The blue line represents your height and the green line is the approximate width of your body. 

We need to get this area in square meter, so the length and width of this rectangle should be in meter.

If you are 6 feet tall, your height in meter is 1.8288 meters.

The width is approximately equal to  1.8288 divided by 4.

Width = 0.4572 meter  

Area = 1.8288 × 0.4572 = 0.8361 meter2

Pressure =
F / A

The force on the bed is 980 newtons

An approximation of the area you cover while you lie down is 0.8361 square meter

Therefore, pressure =
980 / 0.8361

Pressure = 1172.10 pascals.

To find the pressure when you stand up, you need will need to put your right foot next to your left foot and then measure the area.



area = 0.28 × 0.20 = 0.056 meter2

Pressure =
980 / 0.056

The pressure this time is 17500 pascals.

It is a lot more than when you lie down in your bed!

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