Question

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

Answer 1

Initial speed = 80km/ hr = 80x 1000/3600=200/9m/s
Final speed = 60km/ hr=60x 1000/3600= 50/3m/s
t= 5 s
Formula
Final speed = initial speed +acceleration x time
50/3= 200/9+ acceleration x 5
acceleration = - 250/9
acceleration = - 27.7 m/ s^2
Is it correct..

Answer 2

time = t= 5 seconds
initial speed = u = 80km/h = 80*1000/60*60 (meter per second)
u= 800/36 m/s

final speed = v = 60km/h = 60*1000/60*60 m/s
v = 600/36 m/s

acceleration = a = (change in speed)/time
a = (v-u)/t = ((600/36) - (800/36))/5
a= -10/9 ms-2