Question

Mark the correct statements :
(a) The magnitude of the velocity of a particle is equal to its speed.
(b) The magnitude of average velocity in an interval is equal to its average speed in that interval.
(c) It is possible to have a situation in which the speed of a particle is always zero but the average speed is not zero.
(d) It is possible to have a situation in which the speed of the particle is never zero but the average speed in an interval is zero.

Answer 1

(a) The magnitude of the velocity of a particle is equal to its speed.

Explanation:   

At any instant, the magnitude of the velocity is also its speed. So (a) is correct. (b) is incorrect because velocity is displacement in unit time while speed is distance covered in unit time.  (c) is incorrect because if speed is zero in a time interval, that means the particle has not moved in this interval and no distance traveled. So average speed has to be zero.  (d) is incorrect because if the speed of the particle is never zero, means it has traveled some distance.So average speed in the interval will not be zero.