Motion in a straight line – Notes
Position, path length and displacement
Displacement is the change in the position of the body.
Average velocity and average speed
Speed is a scalar whereas velocity is a vector.
The average velocity is the ratio of the change in position or displacement and the time interval in which the displacement occurs.
The unit of velocity is m/s or km/h.
Average speed is the ratio of the total path length and the total time taken for the motion.
The unit for speed is m/s or km/h.
Instantaneous velocity and speed
When a body moves in a straight line, the magnitude of its velocity is equal to its speed.
The velocity at an instant or instantaneous velocity is the limit of the average velocity as the time interval △t becomes infinitesimally small.