A wire fixed at the upper end stretches by length $$l$$ by applying a force $$F.$$ The work done in stretching is

Which of the following statements is correct for any thermodynamic system ?

Two thermally insulated vessels $$1$$ and $$2$$ are filled with air at temperatures $$\left( {{T_1},{T_2}} \right),$$ volume $$\left( {{V_1},{V_2}} \right)$$ and pressure $$\left( {{P_1},{P_2}} \right)$$ respectively. If the value joining the two vessels is opened, the temperature inside the vessel at equilibrium will be

The total energy of particle, executing simple harmonic motion is