Question

A rapidly spinning paddle wheel raises the temperature of 600 mL of water from 21∘C to 25∘C. How much work is done in this process?

Answer 1

Since it is a rapid process, so the Heat released in the process us zero

so

hence all the work goes in the change in internal energy of the system

So

m=density x volume

m=1000 x 600 x 10^-6

m=0.6 kg

Since the temperature increase so the change in internal energy is positive and work is negative

so the work done is