For 20 minutes the bus moved at a speed of 40 km / h, then for 10 km it went at a speed of 50 km / h.

For 20 minutes the bus moved at a speed of 40 km / h, then for 10 km it went at a speed of 50 km / h. Determine the average speed of the bus along the way.

Average bus speed:

Vav. = S / t, where S is the total distance traveled (S = S1 + S2), t is the total travel time of the bus (t = t1 + t2).

Track section S1:

S1 = V1 * t1, where V1 = 40 km / h, t1 = 20 minutes = 1/3 h.

Track section S2:

S2 = 10 km, V2 = 50 km / h; t2 = S2 / V2.

Let’s calculate the average speed:

Vav. = (V1 * t1 + S2) / (t1 + S2 / V2) = (40 * 1/3 + 10) / (1/3 + 10/50) = 43.75 km / h (157.5 m / s ).

Answer: The average speed of the bus is 43.75 km / h or 157.5 m / s.