Question

It is written that if an object travellsequal displacement in equal intervals of time it is said to be in uniform motion but why not equal distance in equal interval of time ?

Answer 1

it is because when a body covers equal distance in equal intervals of time it is not necessary that the direction of motion remains same as distance is not at all concerned with direction whereas if a body covers equal displacement in equal intervals of time, it signifies that the direction of of motion also remains same. If the direction of motion changes when body moves then the body is not moving in uniform motion, so if a body covers equal distance in equal intervals of time, its direction of motion might have changed during the journey,hence, we can't say such body was in uniform motion or not.