question_answer

An electric motor of power 200W is used to drive the stirrer in a water bath. If 60% of the energy supplied to the motor is spent in stirring the water, then calculate the work done on the water in one minute.

Answer:

\[P=200\,W\] \[t=1\,\min =60s\] \[W=?\] \[Efficiency=\frac{Output\,\,power}{Input\,\,power}\] \[\frac{60}{100}=\frac{\frac{w}{t}}{200}\] \[w=\frac{200\times 60\times 60}{100}-7200\,J\]