The point has passed half the way at a speed of 10 km / h. For the rest of the journey, it traveled half the time
| August 17, 2021 | education
The point has passed half the way at a speed of 10 km / h. For the rest of the journey, it traveled half the time at a speed of 18 km / h, and the last section at a speed of 25.2 km / h. Find the average speed of the point.
Task data: S1 = S2 + S3; V1 (point speed on the first half of the journey) = 10 km / h; t2 = t3; V2 (point speed on the second section) = 18 km / h; V3 (point speed on the last leg) = 25.2 km / h.
To find the average speed of a given point, we use the formula: Vav = S / (t1 + t2 + t3) = S / (S / 2V1 + S / (2 * (V2 + V3) / 2)) = 1 / (1 / 2V1 + 1 / (V2 + V3)).
Calculation: Vav = 1 / (1 / 2V1 + 1 / (V2 + V3)) = 1 / (1 / (2 * 10) + 1 / (18 + 25.2)) = 13.67 km / h.
Answer: The average speed of the point is 13.67 km / h.
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