General properties of matter

Elasticity : All most all the substances can be more or less be deformed by applying suitable deforming forces. Some of the substance regain their original shape and size on the removal of deforming force. The property of the substance due to which it regain its original shape and size on the removal of deforming forces is known as elasticity. The substance which completely regain its original shape and size on the removal of deforming forces are known as perfectly elastic but the substance which completely retain its changed dimensions are known as perfectly plastic.

Stress : Whenever a deforming force is applied to bring a change in the dimensions of the substances then the intermolecular force opposes any deformation. This intermolecular force per unit area is known as stress.

In equilibrium the intermolecular force is equal to the applied force. Hence, stress is measured by deforming force per unit area in equilibrium.
Stress= Deforming force/ Area
Types of stress
1. Tensile stress 2. Normal stress & 3. Tangential stress

Strain :The change in dimension per unit original dimension is known as strain.
Types of strain
1. Longitudinal strain 2. volumetric strain & 3. Shear strain.

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Force

In physics force means any influence that causes a Free body to undergo in an acceleration. In other words it is a push or pull that can cause an object with mass to change its velocity. A force has both magnitude and direction which make it vector quantity. Newton's second law, F=ma, can be formulated to state that an object with a constant mass will accelerate in proportion to the net force acting upon and in inverse proportion to its mass, an approximation which breaks down near the speed of light. His original formulation is exact , and does not break down: this version states that the net force acting upon an object is equal to the rate at which its momentum changes.

In short force is an external agent .

Related concepts to accelerating forces include thrust, increasing the velocity of the object, drag, decreasing the velocity of any object, and torgue, causing changes in rotational speed about an axis. Forces which do not act uniformly on all parts of a body will also cause mechanical stress , a technical term for influences which cause deformation of matter. while mechanical stress can remain in solid object, gradually deforming it. thrust is a force which act upon body in opposite direction. It means that it can also called as pseudo force.

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Sir Issac Newton in physics

He has done various research in Physics and discovered well known Theory.

Newton's laws of Motion

First law of motion :

It states that everybody in this universe tends to be in state of uniform motion or in rest unless it is acted upon external force.

Second law of motion :

It states that the rate of change of momentum 0f a body is directly proportional to the applied force on it.

Third law of motion :

It states that to every action there is equal and opposite reaction. Action and Reaction always acts on different body.

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