A steady flow of a liquid of density $$\rho$$ is shown in figure. At point 1, the area of cross-section is $$2 A$$ and the speed of flow of liquid is $$\sqrt{2} \mathrm{~ms}^{-1}$$. At point 2 , the area of cross-section is $$A$$. Between the points 1 and 2, the pressure difference is $$100 \mathrm{~Nm}^{-2}$$ and the height difference is 10 cm . The value of $$\rho$$ is (Acceleration due to gravity $$=10 \mathrm{~ms}^{-2}$$)
A metal tape is calibrated at $$25^{\circ} \mathrm{C}$$. On a cold day when the temperature is $$-15^{\circ} \mathrm{C}$$, the percentage error in the measurement of length is
(Coefficient of linear expansion of metal $$=1 \times 10^{-5}{ }^{\circ} \mathrm{C}^{-1}$$)
A gas is expanded from an initial state to a final state along a path on a $$p$$-$$V$$ diagram. The path consists of (i) an isothermal expansion of work 50 J , (ii) an adiabatic expansion and (iii) an isothermal expansion of work 20 J . If the internal energy of gas is changed by $$-$$30 J , then the work done by gas during adiabatic expansion is
The temperature of the sink of a Carnot engine is 250 K . In order to increase the efficiency of the Carnot engine from $$25 \%$$ to $$50 \%$$, the temperature of the sink should be increased by