Chapter 3, Rest and Motion Kinematics, deals with the concepts of distance and displacement. Although both distance and displacement denote the same meaning, they have a significant difference. Distance is a scalar quantity that denotes the area a person or an object has covered in motion. On the other hand, displacement is a vector quantity, and it indicates how far the object is located from the destination.
Distance and displacement are expressed as d=d1+d2 and x= xf-xi,
where xf = final position and xi= initial position. In case of displacement, it is mandatory to specify the direction of travel. Much similar to distance and displacement, speed and velocity also differ significantly. The speed of an object determines how quickly an object moves. It is a scalar quantity. Moreover, it is the rate at which a person or an object covers distance. Naturally, a fast-moving person or object covers a vast distance in a relatively short span and thus has high speed.
On the contrary, velocity can be defined as the rate at which an object in motion changes its position. Determining the direction of the velocity vector is simple. It is similar to the direction in which it moves. Therefore, the rate or speed of the object does not matter when we consider its direction. Further, the chapter provides a glimpse of acceleration.
Acceleration is also a vector quantity and can be defined as the rate at which an object in motion changes its velocity. Thus, an object is said to be 'accelerating' if it changes its velocity at intervals. Moreover, distance is calculated using the formula
s=ut+1/2at2 . This equation is known as the second equation of motion. It is used to calculate the distance(s) travelled by a body in time (t) with an initial velocity (u) and acceleration (a).