The brakes of a car are applied causing it to slow down at a

The brakes of a car are applied, causing it to slow down at a rate of 10 m/s^2. Knowing that the car-stops 111 100 111. determine (a) how fast the car was travelling immediately before the brakes were applied, (b) the time required for the car to stop.

Solution

1) From the kinematic equations we know that

v² - u² = 2as

where v = final velocity

u = initial velocity

s = displacement = 300 ft =

a = acceleration

Here v =0 (since brakes were applied)

u² = -2as

= 2*10*91.44

u² = 1828.8

u = 42.76 m/s

b) t = 2s/u

t = (2* 91.44)/42.76

t = 4.27sec