JEE Physics Mechanical Properties Of Fluids MCQs Set A

Question. The term ‘fluid’ is used for
(a) Both liquids and gases
(b) Gases only
(c) Liquids only
(d) A mixture of liquid and gas only

Answer: A

Question. Select wrong statement about pressure
(a) None of these
(b) Pressure is always compressive in nature
(c) Pressure is a scalar quantity
(d) Pressure at a point is same in all directions

Answer: A

Question. Gauge pressure
(a) All of these
(b) May be zero
(c) May be negative
(d) May be positive

Answer: A

Question. A barometer kept in an elevator reads 76 cm when it is at rest. If the elevator goes up with some acceleration, the reading will be
(a) < 76 cm
(b) Zero
(c) > 76 cm
(d) 76 cm

Answer: D

Question. A wooden cube just floats inside water with a 200 gm mass placed on it. When the mass is removed, the cube floats with its top surface 2 cm above the water level. What is the side of the cube ?
(a) 10 cm
(b) 12 cm
(c) 8 cm
(d) 6 cm

Answer: A

Question. A block of steel of size 5 × 5 × 5 cm³ is weighed in water. If relative density of steel is 7, its apparent weight is
(a) 6 × 5 × 5 × 5 g wt
(b) 5 × 5 × 5 × 7 g wt
(c) 4 × 4 × 4 × 7 g wt
(d) 4 × 4 × 4 × 6 g wt

Answer: A

Question. A cubical block is floating in a liquid with one fourth of its volume immersed in the liquid. If whole of the system accelerates upward with acceleration g/4, the fraction of volume immersed in the liquid will be
(a) 1/4
(b) 1/2
(c) 3/4
(d) 2/3

Answer: A

Question. A boat carrying a number of stones is floating in a water tank. If the stones are unloaded into water, the water level in the tank will
(a) Fall
(b) Rise
(c) Remain unchanged
(d) Rise or fall depends on the number of stones unloaded

Answer: A

Question. A block of ice is floating in a liquid of specific gravity 1.2 contained in a beaker. When the ice melts completely, the level of liquid in the vessel
(a) Increases
(b) Decreases
(c) First increases then decreases
(d) Remain unchanged

Answer: A

Question. A barometer tube reads 75 cm of Hg. If tube is gradually inclined at an angle of 30° with horizontal, keeping the open end in the mercury container, then find the length of mercury column in the barometer tube
(a) 150 cm
(b) 75 cm
(c) 92.5 cm
(d) 86.7 cm

Answer: A

Question. A metallic sphere weighing 3 kg in air is held by a string so as to be completely immersed in a liquid of relative density 0.8. The relative density of metallic is 10. The tension in the string is
(a) 27.6 N
(b) 32.7 N
(c) 42.5 N
(d) 18.7 N

Answer: A

Question. Two cubical blocks identical in dimensions float in water in such a way that 1st block floats with half part immersed in water and second block floats with 3/4 of its volume inside the water. The ratio of densities of blocks is
(a) 2 : 3
(b) 3 : 4
(c) 1 : 3
(d) 1 : 4

Answer: A

Question. On putting a capillary tube in a pot filled with water, the level of water rises upto a height of 4 cm in the tube. If a tube of half the diameter is used instead, the water will rise to a height of nearly
(a) 8 cm
(b) 11 cm
(c) 4 cm
(d) 2 cm

Answer: A

Question. A flat plate of area 0.1 m² is placed on a flat surface and is separated from it by a film of oil 10^–5 m thick whose coefficient of viscosity is 1.5 N sm^–2. The force required to cause the plate to slide on the surface at constant speed of 1 mm s^–1 is
(a) 15 N
(b) 10 N
(c) 20 N
(d) 25 N

Answer: A

Question. Viscous drag force depends on
(a) All of these
(b) Velocity with which it moves
(c) Size of body
(d) Viscosity of fluid

Answer: A

Question. Which of the following is not the property of an ideal fluid?
(a) Fluid is viscous
(b) Fluid flow is streamline
(c) Fluid flow is irrotational
(d) Fluid is incompressible

Answer: A

Question. A tank is filled with water to a height H. A hole is made in one of the walls at a depth D below the water surface. The distance x from the foot of the wall at which the stream of water coming out of the tank strikes the ground is given by
(a) x = 2 [D (H – D)]^1/2
(b) x = 2 (gD)^1/2
(c) x = 2 [D (H + D)]^1/2
(d) None of these

Answer: A

Question. Soap helps in cleaning clothes, because
(a) It decreases the surface tension of water
(b) It increases the cohesive force between water molecules
(c) It increases the angle of contact
(d) It attracts the dirt particles

Answer: A

Question. On increasing temperature of a liquid, its surface tension generally
(a) Decreases
(b) Increases
(c) Remains constant
(d) First increases and then decreases

Answer: A

Question. The raincoats are made water proof by coating it with a material, which
(a) Increase the angle of contact
(b) Absorb water
(c) Increase surface tension of water
(d) Decreases the density of water

Answer: A

Question. An iron needle slowly placed on the surface of water floats because
(a) Of surface tension
(b) Of its shape
(c) The density of material of needle is less than that of water
(d) It displaces water more than its weight

Answer: A

Question. Two water droplets merge with each other to form a larger droplet. In this process
(a) Energy is liberated
(b) Energy is neither liberated nor absorbed
(c) Energy is absorbed
(d) Some mass is converted into energy

Answer: A