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Physics · MOTION IN A STRAIGHT LINE
हिन्दीAn object covers the first half of a total straight distance with a uniform speed \( v_1 = 20 \text{ m/s} \). The remaining half distance is covered in two equal time intervals with uniform speeds \( v_2 = 30 \text{ m/s} \) and \( v_3 = 50 \text{ m/s} \) respectively. Calculate the average speed of the object over the entire journey.
Correct answer · Option 4
\( 26.67 \text{ m/s} \)
Explanation
For the second half distance \( S \), let time be \( T \). Then \( S = v_2 (T/2) + v_3 (T/2) = 15T + 25T = 40T \implies v_{\text{avg2}} = \frac{S}{T} = 40 \text{ m/s} \). Average speed for entire distance \( 2S \): \( v_{\text{avg}} = \frac{2 v_1 v_{\text{avg2}}}{v_1 + v_{\text{avg2}}} = \frac{2 \times 20 \times 40}{20 + 40} = \frac{1600}{60} \approx 26.67 \text{ m/s} \).
