Question

A car has an initial velocity of $60\text{m/s}$. On application of brakes the car stops after $300\text{m}$. The retardation (deceleration) of the car is

• A. $5{\text{m/s}}^2$
• B. $3{\text{m/s}}^2$
• C. $6{\text{m/s}}^2$
• D. $10{\text{m/s}}^2$

Answer 1

The correct option is C $6{\text{m/s}}^2$

Given, initial velocity of car as $60\text{m/s}$ and stopping distance as $300\text{m}$
We know that
$v^2-u^2=2as\Rightarrow 0^2-{60}^2=2a\times 300$
$\Rightarrow a=\frac{-60\times 60}{2\times 300}=-6{\text{m/s}}^2$
Hence, retardation of the car is $6{\text{m/s}}^2$