Question

The distance covered by an object in a specified direction is________
(A) Speed
(B) Displacement
(C) Velocity
(D) Acceleration

Answer 1

Hint : This question can be answered by looking into the basic definition of each of the terms given in the options. Then by comparing these definitions with the statement given in the question, we can choose the correct option.

Complete step by step answer
We know that the speed of a moving particle is equal to the rate of the distance covered by the particle. It is a scalar quantity, and so it has nothing to do with the direction of the covered distance.
Therefore, the option A is incorrect.
The displacement is defined as the shortest distance between the initial and the final positions of a moving particle. We know that the shortest path possible to reach from one point to the other is nothing but the straight line joining the points. So the distance covered by the particle, or the object along this straight line is called the displacement. Therefore the phrase “specified direction” refers to this straight line only.
So option B is correct.
The velocity is defined as the displacement covered by a particle in one unit time. But the time taken by a particle to cover a distance in a specified direction can be of any value, and not necessarily one unit time.
Therefore, option C is incorrect.
Finally, the acceleration is defined as the rate of change of the velocity of a particle. So it is not directly related to the displacement covered by the particle.
So the option D is also incorrect.
Hence, the correct answer is option B.

Note
We could also attempt this question by considering the dimensions of each of the quantities given in the options. We can see that only displacement has the dimension same as that of the distance. Therefore, option B must only be the correct answer.