The blades of a windmill sweep out a circle of area A. If the wind flows at a velocity v perpendicular to the circle, what is the mass of the air passing through it in time t?

$1. \mathrm{\rho Avt}$
$2. \frac{1}{2}\mathrm{\rho Avt}$
$3. 2 \mathrm{\rho Avt}$
$4. \frac{3}{2} \mathrm{\rho Avt}$

Which one of the following is true from the given statements?

Toricelli’s barometer used mercury. Pascal duplicated it using French wine of density \(984~\text{kg/m}^3.\) The height of the wine column for normal atmospheric pressure is:
1. \(11.5~\text{m}\)
2. \(10.5~\text{m}\)
3. \(9.00~\text{m}\)
4. \(15.0~\text{m}\)

A hydraulic automobile lift is designed to lift cars with a maximum mass of \(3000\) kg. The area of the cross-section of the piston carrying the load is \(425\) cm². What maximum pressure would the smaller piston have to bear?
1. \(3.12\times10^{5}\) Pa
2. \(1.01\times10^{5}\) Pa
3. \(2.94\times10^{5}\) Pa
4. \(6.92\times10^{5}\) Pa

A U-tube contains water and methylated spirit separated by mercury. The mercury columns in the two arms are in level with 10.0 cm of water in one arm and 12.5 cm of spirit in the other. What is the specific gravity of the spirit?

1. 0.8
2. 0.3
3. 0.5
4. 0.7

Glycerine flows steadily through a horizontal tube of a length of 1.5 m and a radius of 1.0 cm. If the amount of glycerine collected per second at one end is 4.0 × 10^–3 kg s^–1, what is the pressure difference between the two ends of the tube?
(Density of glycerine = $1.3\times {10}^3$ kg m^–3 and viscosity of glycerine = 0.83 Pa-sec).
1. 7.9 × 10⁻² Pa
2. 8.9 × 10⁻³ Pa
3. 9.8 × 10⁻² Pa
4. 6.7 × 10⁻³ Pa

What is the excess pressure inside a bubble of soap solution of radius \(5.00\) mm?
(Given that the surface tension of soap solution at the temperature (\(20^{\circ}\)\(\text{C}\)) is \(2.5\times 10^{-2}\) N/m)
1. \(10\) Pa
2. \(20\) Pa
3. \(1.06\times 10^{5}\) Pa
4. \(15\) Pa

A tank with a square base of an area of 1.0 m² is divided by a vertical partition in the middle. The bottom of the partition has a small-hinged door of area 20 cm². The tank is filled with water in one compartment, and an acid (of relative density 1.7) in the other, both to a height of 4.0 m. What is the force necessary to keep the door close?

1. 54.88 N
2. 56.0 N
3. 60.0 N
4. 45.5 N

During a blood transfusion, the needle is inserted in a vein where the gauge pressure is \(2000\) Pa. At what height must the blood container be placed so that blood may just enter the vein?
(The density of whole blood is \(1.06\times10^{3}\) kg/m³).
1. \(0.163\) m
2. \(0.192\) m
3. \(0.157\) m
4. \(0.754\) m