Question

A car moving along a straight highway at a speed of 144 km/h is brought to a stop within a distance of 200m. i) What is the retardation of the car? ii) How long does it take for the car to stop?​

Answer 1

Answer:

First convert 126kmph to m/s ie. 35 m/s.

v^2 - u^2 = 2as

a= acceleration or retardation

v= final velocity =0

u= initial velocity = 35m/s

s= displacement = 200m

0–35^2 = 2a*200 ==> a= -35^2/400 = -1225/400

a= -3.0625m/s^2 is the retardation

Now, v= u +at where t is the time taken

0 = 35 + (-3.0625)t

t= 35/3.0625 = 11.43 seconds approx.