Question

A 4 kW vacuum cleaner is powered by an electric motor whose efficiency is 90%. (Note that the electric motor delivers 4 W of net mechanical power to the fan of the cleaner). What is rate at which this vacuum cleaner supplies energy to the room when running

Answer 1

Answer:$3.6\ kW$

Explanation:

Given

Power Supplied $[tex]P_{input}=4\ kW$[/tex]

Efficiency of the motor $\neta =90\%$

and $\neta =\dfrac{\text{Power output}}{\text{Power input}}$

$\Rightarrow 0.9=\dfrac{P_{out}}{4}$

$\Rightarrow P=0.9\times 4$

$\Rightarrow P=3.6\ kW$

So, vacuum cleaner delivers a power of $3.6\ kW$