Kinematics Question 348
Question: If a car covers $ 2/5th $ of the total distance with $ v _{1} $ speed and $ 3/5th $ distance with $ v _{2} $ then average speed is
Options:
A) $ \frac{1}{2}\sqrt{v _{1}v _{2}} $
B) $ \frac{v _{1}+v _{2}}{2} $
C) $ \frac{2v _{1}v _{2}}{v _{1}+v _{2}} $
D) $ \frac{5v _{1}v _{2}}{3v _{1}+2v _{2}} $
Show Answer
Answer:
Correct Answer: D
Solution:
$ \text{Average speed=}\frac{\text{Total distance travelled }}{\text{Total time taken}} $
$ \text{=}\frac{x}{\frac{2x/5}{v _{1}}+\frac{3x/5}{v _{2}}}=\frac{5v _{1}v _{2}}{3v _{1}+2v _{2}} $
