JEE Physics Mechanical Properties Of Fluids MCQs Set B

Question. The surface tension of a liquid is 5 N/m. If a film is held on a ring of area 0.02 m², its surface energy is about
(a) 2 × 10^–1 J
(b) 3 × 10^–1 J
(c) 2.5 × 10^–2 J
(d) 5 × 10^–2 J

Answer: A

Question. Two soap bubbles having radii 3 cm and 4 cm in vacuum, coalesce under isothermal conditions. The radius of the new bubble is
(a) 5 cm
(b) 7 cm
(c) 3.5 cm
(d) 1 cm

Answer: A

Question. The excess pressure in a soap bubble is double that in other one. The ratio of their volume is
(a) 1 : 8
(b) 1 : 4
(c) 1 : 1
(d) 1 : 2

Answer: A

Question. The kerosene oil rises up in the wick of a lamp
(a) Due to capillaries formed in the wick
(b) Because the wick attract s the oil
(c) Because wick decreases the surface tension of oil
(d) None of these

Answer: A

Question. Ploughing help to retain water by soil
(a) By breaking capillaries
(b) None of these
(c) By creating capillaries
(d) By turning the soil upside down

Answer: A

Question. A capillary tube of radius r is immersed in a liquid and mass of liquid, which rises up in it is M. If the radius of tube is doubled, then the mass of liquid which will rise in capillary tube will be
(a) 2 M
(b) M
(c) M/2
(d) M/4

Answer: A

Question. The atmospheric pressure at a place is 10⁵ Pa. If tribromomethane (specific gravity = 2.9) be employed as the barometric liquid, the barometric height is
(a) 3.52 m
(b) 1.52 m
(c) 4.52 m
(d) 2.52 m

Answer: A

Question. A vertical U-tube of uniform cross-section contains water in both the arms. A 10 cm glycerine column (R.D. = 1.2) is added to one of the limbs. The level difference between the two free surfaces in the two limbs will be
(a) 2 cm
(b) 6 cm
(c) 8 cm
(d) 4 cm

Answer: A

Question. A air bubble rises from bottom of a lake to surface. If its radius increases by 200% and atmospheric pressure is equal to water coloumn of height H, then depth of lake is
(a) 26 H
(b) 9 H
(c) 8 H
(d) 21 H

Answer: A

Question. A piece of gold weighs 10 g in air and 9 g in water. What is the volume of cavity? (Density of gold = 19.3 g cm^–3)
(a) 0.482 cc
(b) 0.382 cc
(c) 0.282 cc
(d) 0.182 cc

Answer: A

Question. A block of ice floats in an oil in a vessel when the ice melts, the level of oil will
(a) Go down
(b) Go up or down depending on quantity of ice
(c) Go up
(d) Remain same

Answer: A

Question. Air streams horizontally past an air plane. The speed over the top surface is 60 m/s and that under the bottom surface is 45 m/s. The density of air is 1.293 kg/m³, then the difference in pressure is
(a) 1018 N/m²
(b) 516 N/m²
(c) 1140 N/m²
(d) 2250 N/m²

Answer: A

Question. At what speed, the velocity head of water is equal to pressure head of 40 cm of mercury?
(a) 10.32 m/s
(b) 2.8 m/s
(c) 5.6 m/s
(d) 8.4 m/s

Answer: A

Question. If the terminal speed of a sphere of gold (density 19.5 kg/m3) is 0.2 m/s in a viscous liquid (density = 1.5 kg/m3), find the terminal speed of a sphere of silver (density = 10.5 kg/m3) of the same size in the same liquid.
(a) 0.1 m/s
(b) 0.133 m/s
(c) 0.4 m/s
(d) 0.2 m/s

Answer: A

Question. The excess pressure inside a spherical drop of water is four times that of another drop. Then their respective mass ratio is
(a) 1 : 64
(b) 1 : 4
(c) 1 : 8
(d) 1 : 16

Answer: A

Question. The work done in blowing a soap bubble of 10 cm radius is (surface tension of soap solution is 0.03 N/m).
(a) 75.36 × 10^–4 J
(b) 37.68 × 10^–4 J
(c) 126.82 × 10^–4 J
(d) 75.36 × 10^–3 J

Answer: A

Question. A glass capillary tube of inner diameter 0.28 mm is lowered vertically into water in a vessel. The pressure to be applied on the water in the capillary tube so that water level in the tube is same as that in the vessel is (surface tension of water = 0.07 N/m and atmospheric pressure = 105 N/m²).
(a) 101 × 10³
(b) 100 × 10³
(c) 99 × 10³
(d) 10³

Answer: A

Question. Water rises to a height of 10 cm in a capillary tube and mercury falls to a depth of 3.42 cm in the same capillary tube. If the density of mercury is 13.6 kg/m³ and angle of contact is 135°, the ratio of surface tension for water and mercury is (angle of contact for water and glass is 0°).
(a) 1 : 6.5
(b) 1.5 : 1
(c) 1 : 3
(d) 1 : 0.5

Answer: A

Question. A spherical drop of water has 1 mm radius. If the surface tension of water is 75 × 10^–3 N/m, then difference of pressure between inside and outside of the drop is
(a) 150 N/m²
(b) 140 N/m²
(c) 70 N/m²
(d) 35 N/m²

Answer: A

Question. A capillary tube is dipped in water and it is 20 cm outside water. The water rises upto 8 cm. If the entire arrangement is put in freely falling elevator the length of water column in the capillary tube will be
(a) 20 cm
(b) 4 cm
(c) 10 cm
(d) 8 cm

Answer: A

Question. If the excess pressure inside a soap bubble is balanced by an oil column of height 2 mm, then the surface tension of soap solution will be (r = 1 cm, density of oil = 0.8 g/cm³)
(a) 3.9 × 10^–2 N/m
(b) 3.9 × 10^–1 N/m
(c) 3.9 × 10^–3 N/m
(d) 3.9 N/m

Answer: A

Question. There is small hole in a hollow sphere. The water enters in it when it is taken to a depth of 40 cm under water. The surface tension of water is 0.07 N/m. The diameter of hole is
(a) 0.07 mm
(b) 0.0007 mm
(c) 0.7 m
(d) 7 mm

Answer: A

Question. A spring balance reads 200 gF when carrying a lump of lead in air. If the lead is now immersed with half of its volume in brine solution, what will be the new reading of the spring balance? specific gravity of lead and brine are 11.4 and 1.1 respectively
(a) 190.4 gF
(b) 180.4 gF
(c) 210 gF
(d) 170.4 gF

Answer: A