A car travels a total distance L. It travels half the distance with speed v_1 and the other half with speed v_2. The average speed of the car is:
- A. \frac{v_1+v_2}{2}
- B. \frac{2v_1v_2}{v_1+v_2} ✓
- C. \frac{(v_1+v_2)L}{2v_1v_2}
- D. 0
Correct Answer: B. \frac{2v_1v_2}{v_1+v_2}
Explanation
When equal distances are covered at different speeds v_1 and v_2, the average speed over the entire journey is the harmonic mean of the two speeds, given by \frac{2v_1v_2}{v_1+v_2}.
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