# The first 1500 m the bus moved at a speed of 25 m / s, then for 40 s it moved at a speed of 20 m / s, after stopping for 70 s

December 31, 2020 | education

| **The first 1500 m the bus moved at a speed of 25 m / s, then for 40 s it moved at a speed of 20 m / s, after stopping for 70 s, the bus covered the last 900 m in 30 s. Find the average speed of the bus along the way.**

In this case, the average speed will be calculated as the ratio of the entire path to the entire time spent:

Vav = Sп / Tп

Given:

t1 = s1 / v1 = 1500/25 = 60 s.

t2 = s2 / v2 = 40 s.

s2 = v2 * t2 = 20 * 40 = 800 m

t3 = 70 s.

s3 = 0 m

t4 = 30 s.

s4 = 900 m

Sп = s1 + s2 + s3 + s4 = 1500 + 800 + 0 + 900 = 3200 m

Tp = t1 + t2 + t3 + t4 = 60 + 40 + 70 + 30 = 200 s.

Answer: Vav = 3200/200 = 16 m / s – average bus speed

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