Question
In a closed insulated container a liquid is stirred with a paddle to increase the temperature, which of the following is true?
A.
$$\Delta E = W \ne 0,\,q = 0$$
B.
$$\Delta E = W = 0,q \ne 0$$
C.
$$\Delta E = 0,W = q \ne 0$$
D.
$$W = 0,\Delta E = q \ne 0$$
Answer :
$$\Delta E = W \ne 0,\,q = 0$$
Solution :
In closed insulated container a liquid is stirred with a paddle to increase the temperature, therefore it behaves as adiabatic process, so for it $$q = 0.$$
Hence, from first law of thermodynamics
$$\eqalign{
& \Delta E = q + W \cr
& {\text{if}},\,\,q = 0 \cr} $$
$$\therefore \,\,\Delta E = W$$ but not equal to zero.