Question

What is the speed of mass $100\text{g}$ having kinetic energy of $20\text{J}$?

• A. $10\text{m/s}$
• B. $15\text{m/s}$
• C. $20\text{m/s}$
• D. $25\text{m/s}$

Answer 1

The correct option is C $20\text{m/s}$

It is given that the kinetic energy$(K.E)$ is

$K.E=20\text{J}$
We also know that, kinetic energy is given by the formula
$=\frac{1}{2}m{v}^2$ where $m$ is mass and $v$ is velocity so the body.

$\Rightarrow \frac{1}{2}m{v}^2=20$
as, $m=100\text{g}=\frac{100}{1000}\text{kg}$

$\Rightarrow K.E=\frac{1}{2}\times \left(\frac{100}{1000}\right)v^2=20$
$\Rightarrow v^2=400$
$\Rightarrow v=20\text{m/s}$

Hence option C is the correct answer.