Question

with what acceleration must the brakes be applied
to stop a vehicle travelling with a speed of 40km/hr
within 20 sec?
​

Answer 1

A car is moving with a speed of 40 m/s. On applying brake, it comes to rest at 20 s. What is the distance between the distance covered by the car before it stops?

Given

initial velocity (u) = 40 km/hr=40×5/18= 11.11111

Final velocity ( V) = 0 km/hr= 0m/s

Time taken ( T ) = 20 second

now first we find the retardation after then we find distance

V= u + at

or, a =( V- u)/T

or a = -11.11/20

or a = - 0.55