The car traveled 50 kilometers at a speed of 20 m / s, the next 20 kilometers at a speed

| September 14, 2021 | education

The car traveled 50 kilometers at a speed of 20 m / s, the next 20 kilometers at a speed of 10 km / h. Determine the average speed of the vehicle over the entire route.

Since the car moved uniformly on each of the two sections of the path, its average speed along the entire path, by definition, is equal to the ratio of the entire distance that it covered S = S₁ + S₂ to the time spent on this path t = t₁ + t₂. Since: v = S: t, then v = (S₁ + S₂): (t₁ + t₂). Moreover, t₁ = S₁: v₁; t₂ = S₂: v₂. We get:

v = (S₁ + S₂): (S₁ / v₁ + S₂ / v₂).

From the condition of the problem it is known that the car traveled S₁ = 50 km = 50,000 m of the way with a speed of v₁ = 20 m / s, the following S₂ = 20 km = 20,000 m of the way – with a speed of v₂ = 10 km / h = 25/9 m / s … Substitute the values ​​of the quantities into the calculation formula:

v = (50,000 m + 20,000 m): (50,000 m / 20 m / s + 20,000 m / (25/9 m / s)); v ≈ 7.2 m / s.

Answer: The average vehicle speed is ≈ 7.2 m / s.



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