Question

A car moving with a speed of 40 m/s comes to rest
after travelling a distance 400 m on applying the
brakes. The acceleration of the car is

Answer 1

Answer:

Acceleration of the car is 2 metre per second sq.

Explanation:

v = 40m/s

u = 0m/s

s = 400m

a = ?

v^2 +u^2 = 2as

(40)^2 + (0)^2 = 2*a *400

1600 + 0 = 800a

a = 1600/800

a = 2m/s^2

Answer 2

Answer:

- 2 m / sec²

Explanation:

Given :

Initial velocity u = 40 m / sec

Final velocity v = 0 m / sec

Distance s = 400 m

We're asked to find acceleration ' a ' :

Using third equation of motion :

= > v² = u² + 2 a s

= > a = ( v² - u² ) / 2 a

Putting values here we get :

= > a = ( 0² - 40² ) / 2 × 400

= > a = - 1600 / 800 m / sec²

= > a = - 2 m / sec²

Here negative sign represent retardation!

Hence we get required answer!