Force || Cause of motion || External effort || Physics||

                          FORCE

As we have experienced that to move a football at rest, someone must kick it Similarly, to throw a stone of wands, we have to give an upward push. To stop a ball rolling down an inclined plane, we have to apply some force in opposite direction of motion, Similarly, when a ball is hit by a bat, its direction of motion changes. We may, therefore, define force as:

Force as an external effort in the form of push or pull, which (i) produces or tries to produce moon in a body at rest, or (ii) stops or tries to stop a moving body, or (iii) changes or tries to change the direction of motion of the body. 

The following examples illustrate the above definition:

(a ) When we push a ball lying on the ground, it starts rolling. The force exerted has thus produced motion in the hall. However, when we push a heavy stone, it does not move. The effort made in this case has only tried to produce motion, but has not succeeded.

(b) A ball falling downwards can be caught easily by our hands. The motion of the ball has thus been destroyed. However, a big piece of rock rolling down a hill cannot be stopped even when we try our best to stop it. 

(c) When a piece of stone tied to one end of a string is whirled in a circle, a constant force has to be Exerted by the hand along the string. This is because the natural tendency of a body is to move along straight line Force is spent in changing the direction of motion of the body from straight line path to the circular path. 

It should be clearly understood that some external agency is always needed to provide the force. In the examples given above, force is applied by our hands. Often, the external agency is in contact with the object a which force is applied. But it is not always necessary. For example, a ball released from some height accelerates downward due to the gravitational pull of earth, which is not in contact with the ball. A magnet attracts an iron nail from a distance, This shows that external agencies of force (e.g. gravitational and magnetic) can exert force on a odd even from a distance.

They need not necessarily be in contact with the object to experience the force. 

Some of the basic forces are:

» Magnetic force

» Electrostatic force 

» Gravitational force

» Tension force

» Normal force

» Electromagnetic force

» Viscous force

» Spring force

» Friction force

» Centripetal force

» Centrifugal force

Basic forces in Nature are: 

» Gravitational force

» Magnetic force

» Electrostatic force 

» Electromagnetic force