If the time interval D t is sufficiently large then the velocity obtained is called average velocity. For as accurate description of motion it is necessary to choose D t as small as possible i.e. D t ® 0; then the velocity obtained is called instantaneous velocity.

As the displacements must be directly proportional to the interval of time hence the ratio of displacement to time interval will be constant whether Dt is sufficiently small or arbitrarily large.

Similar considerations also apply to acceleration also

Even if acceleration keeps on changing with time, we do not find it necessary to consider the rate of change in acceleration for the description of motion, and so on. The reason for this will be found when we study dynamics. The causes of acceleration are forces according to Newton's laws of motion.

Index

2.1 Definitions
2.2 Motion in one Dimension
2.3 Motion in two Dimension

Chapter 3