Distance and Displacement Physics Notes
Distance and Displacement:
Distance and displacement are two quantities that may seem to mean the same thing yet have distinctly different definitions and meanings.
1. Distance: Distance is a scalar quantity that refers to the length of the path covered by the object regardless of its starting or ending position. In other words, distance refers to the length of the entire path travelled by the object.
Unit of distance = meter in M.K.S. system
= centimeter in C.G.S. system
Unit of displacement = meter in M.K.S. system
= centimeter in C.G.S. system.
2. Displacement: Displacement is a vector quantity that refers to the shortest distance between the two positions of the object i.e, the difference between the final and initial positions of the object, in a given time. Its direction is from the initial to final position of the object. It is represented by the vector drawn from the initial position to its final position.
Comparison between distance and displacement:
| Distance | Displacement |
| 1. Distance is a scalar quantity. It has only a magnitude | 1. Displacement is a vector quantity. It has both magnitude and direction. |
| 2. The distance traveled by an object is equal to the length of the path covered. | 2. It is the shortest distance between the initial position and final position of the object in the given time. |
| 3. The distance traveled in a given time is either equal to or greater than displacement. | 3. The displacement of an object can be equal to or less than the distance traveled but never greater than the distance traveled. |
| 4. Distance has positive values. | 4. Displacement can be either positive or negative. |
| 5. Distance depends upon the path. | 5. Displacement does not depend upon the path. It depends upon the starting and endpoints. |
| 6. A reference point, is not used to measure distance. | 6. Displacement is measured with respect to a reference point. |
Generally, it can be said that the magnitude of displacement is equal to the minimum possible distance between two points or
Distance ≥ Displacement.
In a circular motion, if a body starts at point A and comes back at point A then *
Distance = 2 πr
Displacement = Zero
From point A to B
Distance = πr
Displacement = 2r
