Q 11-02-006NEETNEET 2023Top questionEasy
A vehicle travels half the distance with speed $\vartheta$ and the remaining distance with speed $2\vartheta$. Its average speed is:
Answer: (C) $\dfrac{4\vartheta}{3}$
Concept. Average speed $=$ total distance / total time.
Step 1. Time. For a total distance $2d$:
$$t = \frac{d}{\vartheta} + \frac{d}{2\vartheta} = \frac{3d}{2\vartheta}$$
Step 2. Average speed.
$$\frac{2d}{3d/(2\vartheta)} = \frac{4\vartheta}{3}$$
Answer. $\dfrac{4\vartheta}{3}$ (Option C).
Solution by Sreeraj P, M.Sc Physics