A bus decreases its speed from 80 km h^–1 to 60 km h^–1 in 5 s. Find the acceleration of the bus.

Given, initial speed of bus(u) = 80 km h^–1 \( = 80 × \) \( 5 \over 18 \) \( = 22.22 \) m/s

final speed of bus(v) = 60 km h^–1 \( = 60 × \) \( 5 \over 18 \) \( = 16.66 \) m/s

Time taken = 5 s

We know that,
a = \( v - u \over t \)
= \( 16.66 - 22.22 \over 5 \)
= \( - 1.112 \ m/s^2 \)

\(\therefore a = - 1.112 \ m/s^2 \)

The negative sign indicates that the bus is actually not accelerating but retarding.