In a hydraulic lift, compressed air exerts a force $$F$$ on a small piston of radius 3 cm . Due to this pressure the second piston of radius 5 cm lifts a load of 1875 kg . The value of $$F$$ is (Acceleration due to gravity $$=10 \mathrm{~ms}^{-2}$$)
In a $$U$$-shaped tube the radius of one limb is 2 mm and that of other limb is 4 mm . A liquid of surface tension $$0.03 \mathrm{~Nm}^{-1}$$, density $$1500 \mathrm{~kg} \mathrm{~m}^{-3}$$ and angle of contact zero is taken in the tube. The difference in the heights of the levels of the liquid in the two limbs is (Acceleration due to gravity $$=10 \mathrm{~ms}^{-2}$$)
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 $$=1 \times 10^{-5}{ }^{\circ} \mathrm{C}^{-1}$$)