The car drove the first 20 km at 50 km / h, and the next 60 km at 100 km / h.

The car drove the first 20 km at 50 km / h, and the next 60 km at 100 km / h. Determine the average speed of the vehicle along the way.

1) First, we find the time of a car moving at a speed of 50 km / h on a path of 20 km.
t = s / v = 20 km / 50 km / h = 20/50 h = 2/5 h = 0.4 h.
2) Find the time of a car moving at a speed of 100 km / h on a path of 60 km.
t = s / v = 60 km / 100 km / h = 60/100 h = 6/10 h = 3/5 h = 0.6 h.
3) Find the average speed of movement.
To do this, you need to divide the common path by the total time.
s = s1 + s2 = 20 km + 60 km = (20 + 60) km = 80 km.
t = t1 + t2 = 0.4 h + 0.6 h = (0.4 + 0.6) h = 1 h.
Average speed is:
vav = 80 km / 1 h = 80 km / h.
Answer: 80 km / h.