Why is pressure given by force divided by area and not force multiplied by area?

Question

yes i know pressure is given by force per area which means division

that is too obvious in case you dont know

the third and fourth answer are helpful unlike the first two

thumbs down for both of you

Answer 1

if the force is applied evenly over a give area, multiplicating it would suggest that making the area larger would increase the pressure when multiplying actually decreases the pressure over that area..

if you divided it making the area smaller the pressure on the smaller area would be greater.  

Answer 2

Pressure is force PER unit area.  The PER suggests division.

Answer 3

Because the pressure has to expand to cover the entire area.

Pressure is measured in pounds per square inch because the bigger the surface area the less force applied all over the surface.

According to Wikipedia:  http://en.wikipedia.org/wiki/Pressure#Un...

"The SI unit for pressure is the pascal (Pa), equal to one newton per square metre (N·m-2 or kg·m-1·s-2). This special name for the unit was added in 1971; before that, pressure in SI was expressed simply as N/m2.

Non-SI measures such as pound per square inch (psi) and bar are used in parts of the world. The cgs unit of pressure is the barye (ba), equal to 1 dyn·cm-2. Pressure is sometimes expressed in grams-force/cm2, or as kg/cm2 and the like without properly identifying the force units. But using the names kilogram, gram, kilogram-force, or gram-force (or their symbols) as units of force is expressly forbidden in SI. The technical atmosphere (symbol: at) is 1 kgf/cm2. In US Customary units, it is 14.696 psi."

In the case of gases if you increase the volume holding the gas you will decrease the pressure and decrease the temperature.  With hot air balloons you use a burner to increase the temperature inside of the balloon helping to create lift, also because warm air rises.

In the case of tanks the treads have a wider surface area and so spread more of their weight across the ground, meaning that such a heavy vehicle can still travel across muddy terrain without sinking into the mud.

When you go off-road with your car you want to decrease your tire pressure so you can increase the surface area of the tire to give yourself more traction.  On the highway you want to increase your air pressure so you have less contact with the road and so have less drag and improve your gas mileage.

Mines are pressure activated by pressure; an antitank mine requires more pressure so a person stepping on it won't give them enough pressure to detonate them.

Ninja had shoes that actually let them walk on water, because they spread out the surface area allowing the flotation in the shoes to support the person.

Gas stations use a hose with two conductors in it that are kept separate; when a car drives across them the conductors touch and the bell sounds.  When you step on it this isn't enough pressure to activate it.  They use the same system to set up portable traffic monitoring systems.

In the US most traffic intersections, with traffic lights, have a pressure plate that only activates when their is the weight of a motorcycle or car on them telling the light control box that it needs to change.  A moped, bicycle or a person won't have enough weight to tell the traffic control box that there is someone waiting for the light to change.

Answer 4

Pressure is the intensity with which a force is pressing on something, a large force acting on a small area is more likely to cause damage than the same force acting on a larger area. I must admit, am not really sure about what you would want to achieve by multiplying the force with the area. (In other words, I don't know where you are going with this)  

Answer 5

The first two answers are entirely correct. Pressure is the force applied on one unit of surface area, so there is no reason to multiplying force by area.

Answer 6

Because the definition for pressure is force per unit area. And to get unit area, you divide by the area, not multiply.