The bus covered the first 4 km at an average speed of 20 km / h, and for the next 0.3 hours it moved at an average speed
| September 5, 2021 | education
The bus covered the first 4 km at an average speed of 20 km / h, and for the next 0.3 hours it moved at an average speed of 40 km / h. Determine the average speed for the entire journey.
The average speed of the car along the entire path is found by the formula: Vav = S1 + S2 / t1 + t2, where S1, S2 is the distance on different sections of the road, and t1, t2 is the time passed in the given sections.
It is known:
On the first section of the road – S1 = 4 km, Vav1 = 20 km / h,
In the second section – t2 = 0.3 h, Vav2 = 40 km / h.
We find t1 = S1 / Vav1 = 4/20 = 0.5 hours.
Further, in the second section, you need to find the distance:
S2 = t2 * Vav2 = 0.3 * 40 = 12 km.
We get Vav = 4 + 12 / 0.5 + 0.3 = 16 / 0.8 = 20 km / h.
Answer: Vav = 20 km / h.
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