Definitions [6]
Define Distance.
The length of path travelled by a body in certain interval of time is called distance.
Define Displacement.
Displacement of an object between two points is the shortest distance between these two points.
“It is the unique path that can take the body from its initial to the final position.”
The displacement of a moving body is defined as the change in its position along a particular direction
- Displacement is the shortest distance in a straight line between the starting point and the final point, along with a direction. It is a vector quantity, meaning it includes both magnitude (distance) and direction.
- Example: In Ranjit’s case, the displacement is the straight line AD from his house to the school.
- Distance is the total length of the path travelled by a moving object, regardless of the direction. It is a scalar quantity, which means it only has magnitude (size), not direction.
- Example: If Ranjit walks from point A to B to C to D, the distance is the total of AB + BC + CD.
Speed is the distance travelled by an object in a given amount of time without considering the direction.
Formula: Speed = `"Distance traversed" / "Total time."`
"If no force is acting on a body, its velocity does not change, i.e., the body does not accelerate. In other words, if a body is stationary, it will remain stationary. If it is in motion, it will continue moving with the same velocity and in the same direction."
or
"An object continues to remain at rest or in a state of uniform motion along a straight line unless an external unbalanced force acts on it."
or
"Every inanimate object continues to be in its state of rest or of uniform unaccelerated motion unless and until it is acted upon by an external, unbalanced force."
Formulae [1]
\[\vec F\] = m \[\frac{d\vec{\mathrm{v}}}{dt}\] = m\[\vec a\] ... (for constant mass)
Thus, if \[\vec F\] = 0, \[\vec v\] is constant. Hence, if there is no force, velocity will not change. This is nothing but Newton's first law of motion.
