The first half of the journey the car was moving at 60 km / h and the second half at 100 km / h.

The first half of the journey the car was moving at 60 km / h and the second half at 100 km / h. Find the average speed of the car.

Initial data: V1 (vehicle speed in the first half of the journey (S1)) = 60 km / h; V2 (vehicle speed on the second half of the journey (S2)) = 100 km / h; S1 = S2 = 0.5S.

Let’s transform the formula for calculating the average speed of the car:

Vav. = S / t = S / (t1 + t2) = S / (S1 / V1 + S2 / V2) = S / (0.5S / V1 + 0.5S / V2) = 1 / (1 / 2V1 + 1 / 2V2).

Let’s perform the calculation:

Vav. = 1 / (1 / (2 * 60) + 1 / (2 * 100)) = 75 km / h.

Answer: The average vehicle speed is 75 km / h.