Pressure
Pressure is the ratio of the force applied to a surface area. The unit of pressure is measured in pascals (Pa).
The knives we use in our everyday life need to be sharp to be used optimally. A blunt knife is practically useless.
The force that is applied perpendicular to the surface of a particular object gets distributed over it. The lesser the surface area, the higher the pressure, making the knife sharper and easier to use.
Formula of Pressure
Pressure=ForceArea\text{Pressure} = \frac{\text{Force}}{\text{Area}}Pressure=AreaForce
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Pressure is measured in Pa (pascals).
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When a force of 1 newton is applied over an area of 1 meter⊃2;, the pressure generated is 1 pascal.
We can increase or decrease pressure without changing the force by changing the area over which the force is acting:
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Smaller area → Higher pressure
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Larger area → Lower pressure
Example:
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In a sharp knife, the force is distributed over a small surface area, making it very easy to use.
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In a blunt knife, the force is distributed over a large surface area, making the knife harder to use.
Pressure in Fluids
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The particles in a fluid can move in all directions.
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When an object is immersed in water, pressure acts on it in all directions.
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Continuous collisions between fluid molecules generate the pressure.
Pressure in Gases
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Gas particles have random motion.
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When heated, gas particles become excited, increasing their kinetic energy.
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Higher kinetic energy results in more collisions, increasing the pressure exerted.
Equations Involving Pressure
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A brick exerts a force of 25 newtons on an area of 2 meters⊃2;.
Calculation:
Pressure=252=12.5 Pa\text{Pressure} = \frac{25}{2} = 12.5 \text{ Pa}Pressure=225=12.5 Pa -
A bowl exerts a force of 26 newtons on an area of 2 meters⊃2;.
Calculation:
Pressure=262=13 Pa\text{Pressure} = \frac{26}{2} = 13 \text{ Pa}Pressure=226=13 Pa -
An oven exerts a force of 28 newtons on an area of 2 meters⊃2;.
Calculation:
Pressure=282=14 Pa\text{Pressure} = \frac{28}{2} = 14 \text{ Pa}Pressure=228=14 Pa