Difference Between Force and Pressure

Introduction

Force and pressure are the two basic concepts of Physics which are usually wrongly misinterpreted by people. Force and pressure are different entities, and there are vast differences between them, which you can understand only if you have thorough knowledge. Have you ever thought about how football moves? Or how a drawer opens? This happens when the force is applied to an object. In simple words, force is the pull or push which changes the state of motion or the state of rest or the direction of an object.


Have you ever thought why the tools which are used to cut, trim, chop or pierce items have sharp edges? Have you wondered why heavy vehicles have broad tyres? Here comes the concept of pressure, which is the applied force per unit area. This article provides you with some simple and significant differences between force and pressure.


Definition of Force

Force is the push or pull, which arises due to the physical interaction of two objects, and which changes or tends to change the present state of the object. Force is a vector quantity, i.e. it has both magnitude and direction. The magnitude of force determines the amount of force applied to an object.


In simple words, force is the influence which changes or tends to change the state of motion or rest of the body upon which it is applied. The speed and direction describes the state of the motion. When force is applied to an object, it can change its state of motion or its shape.

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When more than one force is applied to an object, the resultant force is called a net Force. When two different forces are subjected to an object in the same direction, then the resultant force is the sum of two forces. And when two different forces are applied in the opposite direction, the resultant force is the difference of the applied forces. 


Broadly, the Forces are of Various Types, These are:

  • Contact Force

  • Muscular Force

  • Frictional Force

  • Non-contact Force

  • Magnetic Force

  • Electrostatic Force

  • Gravitational Force


Definition of Pressure

The amount of force applied per unit area of a surface is called pressure. In simple words, it is the force acting perpendicularly over the surface of the area, which makes it spread about that area. When force is applied to a large surface area, the pressure is low, and when force is applied to a small area, the pressure is high.

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The pressure is the forces spread out by continuous pressing or pushing of two objects with each other. It is calculated as follows:

Pressure = Force / Area

Or, Mathematically: P = F/A

Where:

P is the pressure,

F is the magnitude of the external force, and

A is the surface area of the surface in contact.

Unlike force, the pressure is a scalar quantity, and it has only magnitude. The vector of force acting normal to the surface is the vector element of pressure.


Difference Between Force and Pressure

Basis For Comparison

Force

Pressure

Meaning

Force is a kind of push or pull, resulting from the interaction of two bodies, that can cause the object to accelerate.

Pressure is force extended over ab area, acted upon something, in the direction perpendicular to its surface.

Standard unit

Newton, represented by symbol N.

Pascal, represented by symbol Pₐ.

Instrument

Dynamometer

Manometer

Quantity

Vector Quantity

Scalar Quantity

Applied to

Faces, Edges and Vertices

Faces

Velocity

Can be changed

Cannot be changed


The SI unit of pressure is Pascal (Pa), which is equal to one newton per square meter of area (N/m² or kg/m¹s²). The unit of pressure was first added in 1962, and before that it was expressed in Newtons/Square Meter.


After reading the detailed information about force and pressure, you might have understood the concept behind force and pressure. Some of the daily actions involving force are pushing, pulling, kicking, and throwing while some activities involving pressure are needle with a sharp tip, the pressure exerted by levers, doors with broad handles, etc.

FAQ (Frequently Asked Questions)

1. What is the Difference Between Force and Pressure?

Here we have mentioned some key difference between force and pressure in detail below:

1. The acceleration which results from the push or pull due to the physical contact of two bodies is called force. The force when you normally applied to an area, acting perpendicular to its surface area, is called pressure.


2. The SI unit of Force is Newton and is donated by N. It is equal to 1-kilogram metre per second squared. The SI unit of pressure is Pascal, which is donated by Pa and is equal to 1 Newton per metre squared.


3. Dynamometer is a device used to measure force; whereas a Manometer is used to measure pressure.


4. Force is a vector quantity that has both direction and magnitude, whereas pressure is a scalar quantity having only magnitude.


5. Force can be applied to the face, edges, and vertices of any object, whereas pressure can be applied only to the face of an object.


6. The force applied to an object can change its speed, whereas the pressure applied to the object cannot change the speed of the object.

2. Is Pressure a Result of Force? Or is Force a Consequence of Pressure?

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The pressure is a concept which rises when force is applied to a unit area; in simple words, the pressure is the force per unit area. According to the formula P = F/A, the pressure is directly proportional to the force, i.e. if force is more, the pressure will also be more. The pressure is inversely proportional to area, so if the area is small, the pressure will be more. Pressure cannot exist without force.

3. How Does the Pressure Change When Force is Applied to a Smaller?

The pressure is the force that is divided upon an area. For small areas the pressure is large, and for large areas the pressure is small.


Force applied to a small area causes a significant impact on the object because there is less space for the force to be dissipated; the same force, when applied to a large area, doesn't cause much impact and gets dispersed over the entire region.

4. Is Pressure a Scalar or a Vector Quantity?

The pressure is a scalar quantity; it has only magnitude and no direction.


Let us consider that a force F is applied upon an area ∆A. Pressure will be defined as the standard component of force divided upon area ∆A.


P = (F . n) / ∆ A. Where n is a unit vector normal to the area ∆A.


What if the force is not reasonable to the area? In this case, the pressure will come into effect as a tangential component of stress called shearing stress.