Question

Which of the following statements are incorrect ?
(i) Average velocity is path length divided by time interval.
(ii) In general, speed is greater than the magnitude of the velocity.
(iii) A particle moving in a given direction with a non-zero velocity can have zero speed.
(iv) The magnitude of average velocity is the average speed.

• A. (ii) and (iii)
• B. (ii) and (iv)
• C. (i), (iii) and (iv)
• D. All four

Answer 1

Answer: (C)

Average velocity $=\frac{\text{ Displacement }}{\text{ Time taken }}$
${\vec{v}}_{av}=\frac{\Delta r}{\Delta t}$
(ii) As we know for a given time interval
Distance $\ge \mid$ Displacement
$\therefore$ Average speed $\ge \mid$ Average velocity $\mid$
(iii) A body moving in a given direction with non-zero velocity cannot have zero speed.
(iv) In general average speed is not equal to magnitude of average velocity.