Question

A bus is moving on a straight road with a speed of 126kmh^-1 is brought to rest after 200m. Calculate retardation of the bus.​

Answer 1

Answer:

Use v² = u² + 2as ,  

where v = 0 , and u = 126km/h * 1000 m/1 km * 1 h/3600 s = 35 m/s

and s = 200 m.

0² = (35 m/s)² + 2(200 m) a  

a = -1225 m²/s² / 400 m = -3.063 m/s².

Use v = u + at,

where v= 0, u = 35 m/s ,a = -3.063 m/s²

0 = 35 m/s + (-3.063 m/s²)t ,  

t = (-35 m/s) / (-3.063 m/s²) = 11.42 s

To verify that this answer agrees with the earlier answer:

0.0032 hours * 3600 s/1 hour = 11.52 s

Hope it Helps you !

Answer 2

Explanation:

Use formula,

V^2 - U^2 = 2 × A × S