The car traveled the distance from A to B speed = 36 km / h, and back from B to A speed = 54

| May 17, 2021 | education

The car traveled the distance from A to B speed = 36 km / h, and back from B to A speed = 54. Determine the average ground speed of the flight.

V1 = 36 km / h.

V2 = 54 km / h.

S1 = S2.

Vav -?

To find the average road speed of the vehicle Vav, it is necessary to divide the entire path S traveled by it by the time of its passage t: Vav = S / t.

Since S1 = S2, then the entire path of the car S will be the sum: S = S1 + S2 = 2 * S2.

The travel time of the entire path is expressed by the sum: t = t1 + t2, where t1 is the time of movement from point A to B, t2 is the time of movement from point B to A.

t1 = S1 / V1 = S2 / V1.

t2 = S2 / V2.

t = S2 / V1 + S2 / V2 = (S2 * V2 + S2 * V1) / V1 * V2 = S2 * (V2 + V1) / V1 * V2.

Vav = 2 * S2 * V1 * V2 / S2 * (V2 + V1) = 2 * V1 * V2 / (V2 + V1).

Vav = 2 * 36 km / h * 54 km / h / (54 km / h + 36 km / h) = 43.2 km / h.

Answer: the average ground speed of the vehicle was Vav = 43.2 km / h.



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