What is force? Types of forces in nature

What is force?

Force is a word which we have all heard about. When you push or pull some object you exert a force on it. If you put a body you exert a force away from yourself; when you pull, you exert a force towards yourself. When you hold a heavy block in your hand you exert a large force; when you hold a light block, you exert a small force.

Can non living bodies exert a force? Yes non living bodies can also exert force. If we stand in a great Storm, we feel that the wind is exerting a force on us. When we suspend a heavy block from a rope, the rope holds the block just as a man can hold it in air.

When we comb our dry hair and bring the comb close to small pieces of paper, the pieces jump to the comb. The comb has attracted the paper pieces i.e. the comb has exerted force on the pieces.

Force is an interaction between two objects.The SI unit for measuring the force is called a newton. Approximately, it is the force needed to hold a body of mass 102 gram near the Earth's surface.

Force is a vector quantity and if more than one forces act on a particle we can find the resultant force using the laws of vector addition.

Different forces in nature

In nature, we observe different kinds of forces such as muscular force, force of tension, force of reaction, force of friction, gravitational force, elastic force, wait electrostatic force, magnetic force, nuclear force etc. All these forces can be classified under the following four kinds:

1. Gravitational force
2. Electro magnetic force
3. Nuclear force
4. Weak force

1) Gravitational force

In universe, each particle attracts the other particle due to their masses. Moon revolves around Earth due to gravitation.

The force of attraction between two particles is directly proportional to the product of their masses and inversely proportional to the square of distance between them. The direction of this force is along the line joining the two masses. This force is called the gravitational force.

If two particles of masses m1 and m2 are kept at a a separation r, the gravitational force acting between them is given as:

            

Where G is the universal gravitational constant.

G = 6.67 $\times 10^{-11} N \cdot m^{2}/ kg^ {2}$

Some properties of this force are-

1) It is the weakest force.

2) It is always attractive in nature.

3) It is a long range force.

4) It does not depend on the medium between the             particles.

2) Electromagnetic force

The electromagnetic force, also called the Lorentz force, explains how both moving and stationary charged particles interact. It's called the electromagnetic force because it includes the formerly distinct electric force and the magnetic force; magnetic forces and electric forces are really the same fundamental force. The electromagnetic force is one of the four fundamental forces.

The electric force acts between all charged particles, whether or not they're moving. The magnetic force acts between moving charged particles. This means that every charged particle gives off an electric field, whether or not it's moving. Moving charged particles (like those in electric current) give off magnetic fields.

Some properties of this force are-

1) The force can be attractive as well as repulsive.

2) The force is a long range force.

3) The force depends on the medium between the             charged particles. The force decreases in presence       of dielectric medium between the particles.

Some examples of Electromagnetic forces are - Attraction between two charges, magnetic forces and also friction. Friction is also an Electromagnetic forces.
 To know about friction read this article-CLICK HERE TO KNOW MORE ABOUT FRICTION

3) Nuclear Force

Each atom has a nucleus of diameter nearly 1/10¹⁵m to 1/10¹⁴ m at its centre inside which neutrons and protons are bonded Together by the attractive forces. Although neutron is an uncharged particle and proton is a charged particle, therefore there must be no force between neutron-neutron or proton-neutron and an electric force of repulsion between proton and proton, but there is an equal attractive force between Proton -proton, proton -neutron and neutron-neutron due to which they remain bounded together inside the nucleus. This force is called the nuclear force.

Some properties of this force are-

1) This force is charge-independent.

2) It is a short range force.

3) It is a saturated force that is, the force needed to          isolate a proton neutron from the nucleus is same        whatever may be the number of proton and                  neutron inside it.

4) Weak force

Yet another kind of forces is encountered when reactions involving protons, electrons and neutrons take place. Neutron can change itself into a Proton and simultaneously emit an electron and a particle called Antinutrino. This is called beta minus decay. 

Never think that a neutrino is made up of a Proton, an electron and an Antineutrino. A Proton can also change into neutron and simultaneously emi a positron( and a neutrino). This is called beta plus decay.

The forces responsible for the changes are different from gravitational, electromagnetic or nuclear forces. Such forces are called weak forces. The range of weak forces is very small, in fact but smaller than the size of a proton or a neutron. Thus, its effect is experienced inside such particles only.

Relative magnitude of all four fundamental forces

In increasing order of magnitude, these forces are: gravitational, week electromagnetic and nuclear force.

They are in ratio given as: 1: 10²⁶: 10³⁶: 10³⁹

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