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Physics · MOTION IN A STRAIGHT LINE
हिन्दीA car completes the first one-third of a total distance \( d \) at speed \( 10\text{ m s}^{-1} \), the second one-third at \( 20\text{ m s}^{-1} \), and the final one-third at \( 30\text{ m s}^{-1} \). What is the average speed of the car over the entire distance?
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Correct answer · Option A
\( \frac{180}{11}\text{ m s}^{-1} \)
Explanation
Average speed \( v_{\text{avg}} = \frac{3}{\frac{1}{v_1} + \frac{1}{v_2} + \frac{1}{v_3}} = \frac{3}{\frac{1}{10} + \frac{1}{20} + \frac{1}{30}} = \frac{3}{\frac{11}{60}} = \frac{180}{11}\text{ m s}^{-1} \).
