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

Here, 𝑢 = 80 𝑘𝑚/ℎ = {80 \times 1000\over3600} ms^{-1}={200\over9}ms^{-1}

v = 60 km/h =  {60 \times 1000\over3600} ms^{-1}={150\over9}ms^{-1}

𝑡 = 5 𝑠

Therefore, acceleration, a = ?

We know that, v = u + at

⇒ a = {{v-u} \over t} = {({{150\over9} - {200\over9}})\over5}= {- {50\over9}\over5}=-{10\over9}=-1.1ms^{-2}

Therefore, Acceleration is -1.1 ms ^-2 .