From point a to point in the motorcyclist was moving at a speed of 60 km, the return path, he passed

From point a to point in the motorcyclist was moving at a speed of 60 km, the return path, he passed at a speed of 40 km h, determine the average speed of the motorcyclist for the entire time of movement, the stopping time at point c is neglected.

Given:

v1 = 60 km / h – the speed of the motorcyclist from point A to point B;

v2 = 40 km / h – the speed of the motorcyclist from point B to point A.

It is required to determine the average speed of the motorcyclist movement V (km / h).

Let S be the distance between points A and B.

Then, the entire distance traveled by the motorcyclist is 2 * S (round trip).

From A to B, the motorcyclist traveled in the following time:

t1 = S / v1.

From B to A, the motorcyclist traveled in the following time:

t2 = S / v2.

The total travel time is:

t = t1 + t2 = S / v1 + S / v2 = S * (v1 + v2) / (v1 * v2).

Then the average speed is equal to:

V = 2 * S / (S * (v1 + v2) / (v1 * v2)) = 2 * v1 * v2 / (v1 + v2) =

= 2 * 60 * 40 / (60 + 40) = 4800/100 = 48 km / h.

Answer: the average speed is 48 km / h.