A bus decreases its speed from 80 km h-1 to 60 km h-1 in 5 s. Find the acceleration of the bus.
Firstly, we will change the speed from km/h to m/s, as the given time is in seconds.
Initial speed, u = 80 km/h
= 
= 22.22 m/s (i)
Final speed of bus, v = 60 km/h
= 
= 16.66 m/s (ii)
Time taken, t = 5s (iii)
As we know,
Acceleration, a = 
a = 
a = 
a = - 1.11 m/s2
Here, negative sign shows the negative acceleration of retardation.
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