Question

A body has an initial velocity of $4m{s}^{-1}$ and deceleration of $4m{s}^{-2}$. What is the final velocity after travelling a distance of $2m$?

• A. $4m{s}^{-1}$
• B. $0m{s}^{-1}$
• C. $\sqrt{3}2m{s}^{-1}$
• D. $16m{s}^{-1}$

Answer 1

The correct option is B $0m{s}^{-1}$

Let $u$ be the initial velocity of the body, $v$ be the final velocity, $a$ be the acceleration and $s$ be the distance traveled.
Given, $u=4m{s}^{-1}$, $a=-4m{s}^{-2}$ (since the body is decelerating), and $s=2m$
From the third equation of motion,
$v^2$ = $u^2$ + $2as$ $\Rightarrow v^2=4^2+(2\times -4\times 2$)
$\Rightarrow v=\sqrt{4^2+(2\times -4\times 2)}=0m{s}^{-1}$