Question

A car has an initial velocity of $100\text{m/s}$. On the application of brakes the car stops at $200\text{m}$. The acceleration of the car will be

• A. $-25{\text{m/s}}^2$
• B. $-50{\text{m/s}}^2$
• C. $25{\text{m/s}}^2$
• D. $50{\text{m/s}}^2$

Answer 1

The correct option is A $-25{\text{m/s}}^2$

Given, $u=100\text{m/s},s=200\text{m},v=0$
$\because v^2=u^2+2as$
$0=(100{)}^2+2(a)\times 200$
$-10000=400a$
$\Rightarrow a=\frac{-10000}{400}=-25{\text{m/s}}^2$