During the first half of the journey, the car moved at a speed 8 times faster than in the second half of the journey.

During the first half of the journey, the car moved at a speed 8 times faster than in the second half of the journey. The average speed along the entire path is 16 km / h. Find the speed on the second half of the trip.

Initial data: V1 (vehicle speed in the first half of the journey) = 8V2 (vehicle speed in the second half of the journey); Vav. (average vehicle speed) = 16 km / h; S1 = S2 = 0.5S.

Let’s compose a formula for calculating the speed on the second half of the journey:

Vav. = S / t = S / (t1 + t2) = S / (S1 / V1 + S2 / V2) = S / (0.5S / 8V2 + 0.5S / V2) = 1 / (1 / 16V2 + 1 / 2V2) = 1 / (9 / 16V2) = 16V2 / 9.

V2 = 9Vav. / 16.

V2 = 9 * 16/16 = 9 km / h.

Answer: The speed of the car on the second half of the journey is 9 km / h.