## Saturday, November 8, 2014

### Distance and Displacement Comparison

The entire physics subject can be broadly divided into two categories.They are classical physics in modern physics. For the science to be called as a classical physics, it shall be developed at the beginning of science.The classical physics deals with the macroscopic bodies that what we are able to see. In the other way classical physics is a macroscopic physics that we can directly experience up to some extent. If a time deadline has to be kept,it is developed before 1900 A.C. Newton is being treated as the father of the classical mechanics. His laws of motion has given a crystal clear clarity that how the body moves which are macroscopic in nature when force is applied.

Modern physics deals with the microscopic bodies like electrons and protons.It is obvious that we cannot see them therefore we have to depend on experimental results to draw the conclusions.

Translatory motion is one of the basic topics of  classical mechanics. It basically deals with the bodies that are moving along a straight line.The Newton laws are actually applied for a elementary part of a body called particle. A particle is a body of negligible dimensions. As the body is a combination of so many particles the rules that are developed for the particle can be applied for the body also.

The branch of physics which deals with the motion of the body without worrying about the forces acting on it could be called as kinematics. In the other way this emotion of your body along only one dimension.To study this one-dimensional motion we need to know some basic terms.

The first set of the fundamental terms that we are going to define here are rest and motion.These words are in fact relative. We are saying these words with respect to the earth because we are on the earth.

The particle who doesn't change its position with respect to time and surroundings is said to be in the state of rest. Obviously the particle who is changing its position continuously with respect to the time and surroundings is said to be in the state of motion.

Next we would like to define a set of terms called distance and displacement.Distances the actual path followed by a body between its initial and final positions,where as the displacement is the shortest possible distance between initial and final positions in the specified direction.

Between any two specified points there may be different distances because there may be different paths but the displacement is going to be only one as it is going to be the shortest possible distance between the two specified points.It is quite possible that a distance can be greater than displacement is the path chosen could be greater than the shortest possible path. But displacement will never be greater than that of distance and get the best displacement is equal to distance.

Distances are scalar quantity which has only magnitude. Displacement is a vector quantity which has both magnitude and direction.As it is explained in the previous lessons some physical quantities demands both magnitude and direction to understand completely and the physical quantities are being called as vectors.

Now let us consider solving a problem on distance and displacement. Let us consider a body in circular motion of radius r.Find the distance and displacement covered by your body when it covers one fourth of the circular motion.

Let us consider solving another problem where a circular body of radius R is moving on a smooth horizontal surface.Find its displacement when half of circular motion is completed ?

The problem is solved as shown and here displacement is simple shortest possible distance between initial and final positions.

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