The cyclist travels over rough terrain for 11 km. 6 km uphill, he moved at a speed of 7.2 km / h

The cyclist travels over rough terrain for 11 km. 6 km uphill, he moved at a speed of 7.2 km / h, the rest of the way (5 km) from the mountain at a speed of 36 km / h. What is its average speed?

Let’s find the time intervals for which the individual sections of the path were covered:
V1 = 7.2 km / h = 7200 m / 3600 s = 2 m / s;
V2 = 36 km / h = 36,000 m / 3600 = 10 m / s;
t1 = 6000 m / (2 m / s) = 3000 s;
t2 = 5000 m / (10 m / s) = 500 s.
Total travel time: t = t1 + t2 = 3500 s.
Average speed Vc = S / t = 11,000 m / 3500 s = 3.143 m / s.
Speed in initial units: Vc = 3.143 * (3600/1000) = 11.3 km / h.
Answer: 3.143 m / s or 11.3 km / h.