1. What is the average speed of a Formula 1
racing car, if half of the laps are covered at
100 km/h and the other half at 300 km/h?

2. What is the law of uniform motion?
v s/t
We obtain the inversion:
s vt and t s/v

3. You might think the answer is the average of 100 and 300
(100+300)/2 = 200 km/h
wrong!!!!

4. If the distance s (half of rpm) is gone at a velocity of 100 km/h it
takes the time t1 = s/100;
If the same distance s is gone at a velocity of 300 km/h instead, the
necessary time will be t2 = s/300.
If we divide the total distance of 2s to the total time taken
t =t1 +t2 = s/100 + s/300 (= 4s/300 = 2s/150)
we find: vm = 2s/(2s/150) = 150 km/h
then we can write: vm = s / (2s/150)/2 = s/ tm
So we divide the common distance to the average time