What is Pressure?
A perpendicular force acting on the surface of an object per unit area on which it is acting is called Pressure.
The SI unit of pressure is Newton per meter squared. It is also called Pascal, denoted by Pa.
What is the Formula for Pressure?
Pressure =𝐹𝑜𝑟𝑐𝑒 𝑎𝑝𝑝𝑙𝑖𝑒𝑑 𝑜𝑛 𝑎𝑛 𝑜𝑏𝑗𝑒𝑐𝑡 / 𝑆𝑢𝑟𝑓𝑎𝑐𝑒 𝑎𝑟𝑒𝑎 𝑖𝑛 𝑐𝑜𝑛𝑡𝑎𝑐𝑡
From the formula, we can understand that to increase the pressure on an object, we can either increase the force applied (numerator) or decrease the area of contact with that object (denominator). Let us understand this concept using some daily life examples.
Creating a High Pressure
Nail
When hammering a nail, we keep the pointed end faced towards the wall. This is because the tip of the nail has a very small area compared to the flat surface of the nail. This reduces the area of contact with the wall to a great extent in the first case.
Hence, the pressure applied by the tip on the wall is greater than the pressure applied by the flat surface. This is the reason why it is easy for the tip of the nail to penetrate through the wall.
Drill machine
Using the same concept, we use a drill machine with a pointed tip. This reduces the area in contact and hence increases the pressure applied by the drilling machine.
This makes it easier to drill a hole in the wall.
Axe
When cutting a tree, we use the sharper end of the axe as it has a low surface area, thereby reducing the area in contact with the tree.
Knife
And lastly, cutting of vegetables is done using the sharper end of the knife as it reduces the surface area in contact, thereby increasing the pressure applied.
Creating a Low Pressure
Snow Shoes
Walking on the snow is difficult because the snow is soft and the less surface area of our normal shoes leads to higher pressure on the ground. This makes our feet get stuck in the snow.
To prevent this, we wear snow-shoes which have a greater surface area compared to our normal shoes. This decreases the pressure we are applying on the ground while walking and hence making it easier to walk on the snow without getting stuck.
Battle Tanks
The same concept is used in battle tanks that are huge in size. In these tanks, the wheels are on steel tracks and are not touching the ground.
If the wheels run on the ground, due to less contact area with the ground, the pressure on the ground will be massive. To prevent this, we attach tracks on its wheels that have a much larger area of contact with the ground. This reduces the pressure on the ground to a great extent.
Summary
|
Pressure |
Perpendicular force acting on the surface of an object per unit area on which it is acting |
| Formula for Pressure | Pressure = 𝐹𝑜𝑟𝑐𝑒 𝑎𝑝𝑝𝑙𝑖𝑒𝑑 𝑜𝑛 𝑎𝑛 𝑜𝑏𝑗𝑒𝑐𝑡
𝑆𝑢𝑟𝑓𝑎𝑐𝑒 𝑎𝑟𝑒𝑎 𝑖𝑛 𝑐𝑜𝑛𝑡𝑎𝑐𝑡 |
|
SI Unit of Pressure |
Newton per meter square ( 𝑁 ) or Pascal
𝑚2 (Pa) |
|
High Pressure |
If the area of contact with the object on which the force is applied decreases, it results in higher pressure being applied on that object |
| Low Pressure | If the area of contact with the object on which the force is applied increases, it results in lesser pressure being applied on that object |
Did you know?
Submarines are designed specifically to withstand high pressures when they are deep underwater.
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