|
Power and Efficiency
Example 1
An electric motor takes 20 s to lift a box of mass 20kg to a height of 1.5 m. Find the amount of work done by the machine and hence find the power of the electric motor.
Answer:
Work done,
W = mgh = (20)(10)(1.5) = 300J
Power,
\begin{gathered}
P = \frac{W}
{t} \hfill \\
P = \frac{{300}}
{{20}} = 15W \hfill \\
\end{gathered}
Refrigerator
- Always remember to close the door of refrigerator.
- Open the refrigerator only when necessarily.
- Always keep the cooling coil clean.
- Defrost the refrigerator regularly.
- Choose the refrigerator with capacity suitable for the family size.
- Refrigerator of large capacity is more efficient compare with refirgerator of small capacity.
Table of Content
|
