A Bus Decreases its Speed from 80 kilometres per hour to 60 km per hour in 5 seconds, find the acceleration of the bus

Answer: Initial speed of the bus = 80 kilometres per hour 

Final speed of the bus = 60 km per hour

Time period, t = 5 seconds 

Firstly, convert both initial and final velocity from km per hour to metre per hour. 

Initial velocity (U) = 80 km/hr 

                         = 80 × 5/18

                         = 400/18 

                         = 22.2 m/sec 

Final velocity (V) = 60 km/hr 

                        = 60 × 5/18 

                        = 300/18 

                       = 16.6 m/sec

This question is solved by using the acceleration formula, which demonstrates the relation between speed, acceleration and time. 

So, the formula is, 

Acceleration, a = (V – U) / t 

Putting the values of V, U and t. 

a = (16.6 – 22.2)/5

a = -5.6/5

a = -1.12 m/s²

So, the acceleration is -1.12 m/s².