Contact force:
We
are familiar with different types of force in our daily lives. Nature of them
is of
different
types. Some of them are produced due to direct contact between two bodies. In
addition,
there are some forces which do not need direct contact between two bodies.
The
force which needs direct contact between two bodies to be created is defined as
contact
force. When we push or pull a body with hand our hand exerts a force on the
body
at that time. This push or pull force is contact force. Since this force is the
consequence
of the direct contact between the hand and the body. The examples of
contact
forces are- frictional force, pulling force and the force created during
collision.
When
a body tends to move or move over another body, then a resistive frictional
force
is
produced against the motion between the contact surfaces of two bodies. Here
the
frictional
force is produced due to direct contact between the surfaces of the two bodies.
We
apply pulling force on a box when we pull it over the floor. At that time
frictional
force
is produced opposite to the motion of the box.
Non-Contact force:
The
force which acts without direct contact between two bodies is called
non-contact
force.
The attractive gravitational force between two bodies, the attractive or
repulsive
electric
force between two charged bodies, the attractive or repulsive force between two
poles
of two magnets, the force of attraction acting between a magnet and a magnetic
material
are the examples of non-contact force or distant force.
Do yourself: Release a pen or pencil or any object from your hand.
The
body will fall down. Something is pulling the body downward certainly. Who is
pulling?
Here, the earth is pulling the body towards it, though there is no direct
connection
between the body and the earth i.e. the earth is not in contact with the body.
Here
the earth is applying force of gravitation on the body. The force of
gravitation is a
non-contact
force. Any two body of the universe exert force of gravitation on each other.
When
the earth exerts force of gravitation on another body, then this force is
called
gravity.
Though
we observe different kinds of force in nature, fundamental force are of four
types.
Rest of them is some forms of these fundamental forces. The forces which are
root
or
independent i.e. the forces which are not produced from some other forces or
not any
forms
of some other forces are called fundamental forces. Instead, other forces are
some
forms
of these fundamental forces.
52
Physics
The
four fundamental forces which exist in nature are:
1.
Force of gravitation
2.
Electromagnetic force
3.
Weak nuclear force
4.
Strong nuclear force
Force of Gravitation:
In
this universe every body attracts each other by a force towards them. The
mutual
attraction
between any two bodies of the universe is called gravitation. This attraction
occurs
due to mass of the bodies. The force of gravitation is comparatively weak among
the
fundamental forces. Weight of us is the consequence of gravitation. The planets
of
the
solar system are revolving round the Sun due to force of gravitation. The range
of
gravitation
extends to infinity.
Electromagnetic force:
The
electromagnetic force is defined as the force exerted by two charged particles
or
bodies
on each other due to their charges. This force may be of both types- attractive
or
repulsive.
When the charged particles are at rest, only electric force works between
them.
The magnetic force is created simultaneously in addition to the electric force
between
the particles when the charged particles are mobile. The force of attraction or
repulsion
between two magnetic poles is also electromagnetic force. The electric force
acting
between two charged fundamental particles is more powerful than the force of
gravitation
between them. Nevertheless, electric force is of medium type considering
strength.
Frictional force, spring force etc. are produced due to electric forces between
the
charged particles.
Weak nuclear force
The
short range and small magnitude force that exists between the fundamental
particles
within
the nucleus is called weak nuclear force. Due to this force the nucleus becomes
unstable
and beta decay occurs. Most of the radioactive disintegration occurs due to
weak
nuclear force. The range of this force is less than 10-16 m.
Strong nuclear force
It
is known that there are two particles namely proton and neutron within the
nucleus of
an
atom. These particles are called nucleon. The strong force that exists between
two
nucleons
within the nucleus of an atom is called strong nuclear force. This force bounds
the
nucleons together. The strong nuclear force is responsible for the stability of
the
nucleus.
This force is very short range and attractive. The range of this force is 10-15 m
which
is the radius of the nucleus. This force is the strongest among the fundamental
forces.
