Question

In, a thermos bottle cold coffee is rigorously shaken then

• A. No work is done
• B. temp remains unchanged
• C. temp rise
• D. temp falls
• E. work done is numerically equal to gain in internal energy

Answer 1

Answer: (C), (E)

work done is numerically equal to gain in internal energy
temp rise

Shaking of flask imparts kinetic energy to the fluid. Hence work is done on the system$\Rightarrow \Delta W<0$
Flask has adiabatic walls. Hence no heat passes through. Hence at equilibrium applying first law,
$\Delta U=-\Delta W>0\Rightarrow \Delta T>0$
Hence options c and e are correct