Question

We have an electric kettle rated at $60V,5A$ that runs for $5$ minutes. The same amount of energy is used to accelerate a mass of $10kg$. What is the velocity attained​ by the​​​​​​ mass?

• A. $100\sqrt{5}m{s}^{-1}$
• B. $50\sqrt{5}m{s}^{-1}$
• C. $30\sqrt{5}m{s}^{-1}$
• D. $60\sqrt{5}m{s}^{-1}$

Answer 1

The correct option is D

$60\sqrt{5}m{s}^{-1}$

Given: Voltage, $V=60V$
Current, $I=5A$
Mass of the kettle, $m=10kg$
Time, $t=5\text{minutes}$

The energy used by kettle is:
$E=VIt$
$E=60\times 5\times 5\times 60$
$E=90000J$

Now, this amount of energy is used to drive the ball.
$\Rightarrow 90000=\frac{1}{2}\times m\times v^2$​
$\Rightarrow v^2=\frac{90000\times 2}{10}$
$\Rightarrow v=\sqrt{18000}$
or, $v=30\sqrt{20}m{s}^{-1}$
or, $v=60\sqrt{5}m{s}^{-1}$