Physics terms

Physics is a science dealing with nature and natural phenomena. It can also be defined as the stytematic study of properties of material bodies in nature under different physical conditions. Measurement of physical quantities such as length, mass and time is involved in the understanding of the properties of material bodies. Thus, physics can also be defined as the science of accurate measurement of physical quantities.

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ATOM

What is an atom ?

If Idea of divisibility of matter was considered long back in India and elsewhere in the world. Indian philosopher, Maharshi Kanad postulated that if we go on dividing matter (Padarth), we shall get smaller and smaller particles and a limit will come when we will come across the smallest particle and beyond this further division will not be possible. He names the particles Pramanu. This work in India was done nearly five hundred years B.C.

An atom is the smallest particle of an element which can exist and retains all the chemical properties of element.

All matter whether element, compound or mixture is composed of small particles called atoms.

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ELEMENT

What is an element?

An element is basic form of matter that cannot be broken down by chemical reaction into simpler substances.

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GRAVITY

Gravitation is the force of attraction that acts between all objects because of their mass. An object's mass is its amount of matter. Because of gravitation, an object that is near Earth falls toward the surface of the planet. An object that is already on the surface experiences a downward force due to gravitation. We experience this force on our bodies as our weight. Gravitation holds together the hot gases that make up the sun, and it keeps the planets in their orbits around the sun. Another term for gravitation is the force of gravity.

People misunderstood gravitation for centuries. In the 300's B.C., the Greek philosopher and scientist Aristotle taught the incorrect idea that heavy objects fall faster than light objects. People accepted that idea until the early 1600's, when the Italian scientist Galileo corrected it. Galileo said that all objects fall with the same acceleration unless air resistance or some other force acts on them. An object's acceleration is the rate of change of its velocity (speed in a particular direction). Thus, a heavy object and a light object that are dropped from the same height will reach the ground at the same time.

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MATTER

What is matter ?

Matter is anything that has mass and occupies space. Indian and greek philosophers have attempted to analyse and classify matter in the form of five elements; Air, Earth, Fire, Sky and Water.

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MOLECULE

What is molecule ?

A molecule is a definite group of atoms that are chemically bonded together, i.e. tightly connected by attractive forces. Thus, a molecule is the smallest particle of an element or of a compound which can exist alone or freely under ordinary conditions and shows all the properties of that (element or compound)

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WORK / ENERGY

Work

Work done on a body is defined as the magnitude of the force multiplied by the distance moved by the body in the direction of the applied force.

Energy

An object having capability to do work is said to possess energy. Energy has the same unit as that of work.

Kinetic Energy

A body in motion possesses what is known as kinetic energy of the body.

Potential Energy

The energy possessed by the body due to change of position or shape is termed as potential energy.

Mechanical Energy

The kinetic energy and potential energy together are different form of what may be commonly referred to as mechanical energy.

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EINSTEIN GENERAL THEORY OF RELATIVITY

Einstein’s general theory of relativity (1915)

The theory of gravity in which gravity is explained as a curvature in four-dimensional space time caused by the presence of mass or energy. It provides a set of equations that determines how much curvature is generated by any given distribution of mass or energy. It is a theory that we use to describe gravity at the level of the very large.

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EINSTEIN SPECIAL THEORY OF RELATIVITY

Einstein’s special theory of relativity (1905)

Einstein’s new view of space and time. The theory is based on the idea that the laws of science should be the same for all freely moving observer, no matter what their speed. The speed of light remains unchanged, no matter what the velocity of the observer measuring it is.

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NEWTON'S FIRST LAW OF MOTION

Newton's First law of motion

A body continues to be in a state of rest or of uniform motion along a straight line unless an external force acts upon it.

According to the first law, a body tends to remain at rest if it is at rest and continues to move along a straight line if it is in motion unless an external force is applied on it. In other words, all bodies resist a change in their state of motion. This tendency of bodies to resist change in the state of their motion is called inertia. Newton’s first law of motion is, therefore, called inertia. Thus, Newton’s first law of motion is, therefore, also known as the law of inertia.

The mass of a body is a measure of its inertia.

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NEWTON'S SECOND LAW OF MOTION

Newton's second law of motion

The rate of change of momentum of a body is directly proportional to the force and takes place in the same direction as the force.

The acceleration produced in a body is directly proportionate to the force acting on it.

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NEWTON'S THIRD LAW OF MOTION

Newton's Third law of motion

To every action there is an equal and opposite reaction and they act on two different bodies.

This tells us that at least two bodies are necessary for a force to exist. A Force is either an action or a reaction.

NEWTON'S FIRST LAW OF MOTION

Newton's First law of motion

A body continues to be in a state of rest or of uniform motion along a straight line unless an external force acts upon it.

According to the first law, a body tends to remain at rest if it is at rest and continues to move along a straight line if it is in motion unless an external force is applied on it. In other words, all bodies resist a change in their state of motion. This tendency of bodies to resist change in the state of their motion is called inertia. Newton’s first law of motion is, therefore, called inertia. Thus, Newton’s first law of motion is, therefore, also known as the law of inertia.

The mass of a body is a measure of its inertia.

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NEWTON'S SECOND LAW OF MOTION

Newton's second law of motion

The rate of change of momentum of a body is directly proportional to the force and takes place in the same direction as the force.

The acceleration produced in a body is directly proportionate to the force acting on it.

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NEWTON'S THIRD LAW OF MOTION

Newton's Third law of motion

To every action there is an equal and opposite reaction and they act on two different bodies.

This tells us that at least two bodies are necessary for a force to exist. A Force is either an action or a reaction.

ATOM

What is an atom ?

If Idea of divisibility of matter was considered long back in India and elsewhere in the world. Indian philosopher, Maharshi Kanad postulated that if we go on dividing matter (Padarth), we shall get smaller and smaller particles and a limit will come when we will come across the smallest particle and beyond this further division will not be possible. He names the particles Pramanu. This work in India was done nearly five hundred years B.C.

An atom is the smallest particle of an element which can exist and retains all the chemical properties of element.

All matter whether element, compound or mixture is composed of small particles called atoms.