Question

A body of mass $1kg$ has kinetic energy $1J$ when its speed is

• A. $0.45\raisebox{1ex}{$m$}\!\left/ \!\raisebox{-1ex}{$s$}\right.$
• B. $1\raisebox{1ex}{$m$}\!\left/ \!\raisebox{-1ex}{$s$}\right.$
• C. $1.4\raisebox{1ex}{$m$}\!\left/ \!\raisebox{-1ex}{$s$}\right.$
• D. $4.4\raisebox{1ex}{$m$}\!\left/ \!\raisebox{-1ex}{$s$}\right.$

Answer 1

The correct option is C

$1.4\raisebox{1ex}{$m$}\!\left/ \!\raisebox{-1ex}{$s$}\right.$

Step 1: Given

Mass of body$m=1kg$

The kinetic energy of the body $K.E=1J$

Step 2: Calculate the kinetic energy,

The kinetic energy in terms of mass and velocity is,

$$\begin{gathered} \Rightarrow K.E=\frac{1}{2}m{v}^2 \\ \Rightarrow 1=\frac{1}{2}\times 1\times v^2 \\ \Rightarrow v^2=2 \\ \Rightarrow v=\sqrt{2} \\ \Rightarrow v=1.41\raisebox{1ex}{$m$}\!\left/ \!\raisebox{-1ex}{$s$}\right. \end{gathered}$$

Thus, we conclude that the velocity of the body is $v=1.41\raisebox{1ex}{$m$}\!\left/ \!\raisebox{-1ex}{$s$}\right.$.

Hence, option C is the correct answer.