Free NEET Physics multiple-choice questions on Fluid Pressure & Buoyancy. Attempt each question and reveal the answer with a full explanation.
A solid sphere sinks in a liquid with terminal velocity v . If the density of the sphere is 3 times the density of the liquid, the buoyant force on the sphere is: W/3 W/2 W 2W/3 The bulk modulus of a spherical object is B . If it is subjected to uniform pressure p , the fractional decrease in radius is: p 3B 3p B p B B 3p A hydraulic lift is used to lift a car of mass 3000 kg . The area of cross-section of the piston carrying the car is 425 cm 2 . What pressure must the smaller piston endure if the car is to be lifted? (Take g = 9.8 m/s 2 ) 6.92 10 5 Pa 3.14 10 5 Pa 1.58 10 6 Pa 9.21 10 4 Pa The bulk modulus of an ideal gas during an isothermal process is equal to: Its pressure P The product of pressure and volume PV Zero P (where is the ratio of specific heats) An object weights 50 g in air, 40 g in water and 45 g in a liquid. The density of the liquid is: 0.5 g/cm 3 1.2 g/cm 3 0.8 g/cm 3 1.5 g/cm 3 A block of wood floats in water with (4/5) th of its volume submerged. If the same block floats in a liquid with density 1.2 10 3 kg/m 3 , what fraction of its volume is submerged? 2/3 1/2 3/4 5/6 A vessel contains oil (density 0.8 g/cm 3 ) floating over mercury (density 13.6 g/cm 3 ). A homogeneous sphere floats with half its volume immersed in mercury and the other half in oil. The density of the material of the sphere is: 7.2 g/cm 3 6.4 g/cm 3 3.3 g/cm 3 12.8 g/cm 3 A sphere, a cube and a thin circular plate, all of same material and same mass are initially heated to same high temperature. Which of these will cool fastest? Plate Cube Sphere All will cool at same rate The compressibility of water is 4 10 -5 per unit atmospheric pressure . The decrease in volume of 100 cm 3 of water under a pressure of 100 atm will be: 0.4 cm 3 4 10 -5 cm 3 0.04 cm 3 4 cm 3 A glass of water is filled to the brim at 4 C . What happens if the temperature is either increased or decreased slightly? Water overflows in both cases Water level goes down in both cases Water overflows only when temperature is increased Water overflows only when temperature is decreased The Bulk Modulus of an ideal gas during an adiabatic process is: P P Zero Infinite What is the pressure at a depth of 10 m in a swimming pool filled with water? ( g = 10 m/s 2 , P atm = 1.01 10 5 Pa ) 2.01 10 5 Pa 1.01 10 5 Pa 1.00 10 5 Pa 0.50 10 5 Pa A body floats in a beaker of water. If the beaker is allowed to fall freely, the upthrust (buoyant force) on the body will be: Zero Equal to its weight Twice its weight Unchanged A container filled with a liquid of density is moving upwards with an acceleration a . The difference in pressure between two points in the liquid separated by a vertical distance h is: h (g + a) h (g - a) h g h a A solid sphere of radius R and bulk modulus B is surrounded by a liquid in a cylindrical container. A massless piston of area A floats on the surface of the liquid. When a mass M is placed on the piston to compress the liquid, the fractional change in the radius of the sphere R/R is: Mg/(3AB) Mg/(AB) 3Mg/(AB) Mg/(4AB) A solid object floats in water with 3/4 of its volume submerged. When the same object is placed in a liquid, it floats with 2/3 of its volume submerged. The density of the liquid is: 1125 kg/m 3 888 kg/m 3 1333 kg/m 3 750 kg/m 3 A liquid of density is rotating in a cylindrical vessel of radius R with angular velocity about its vertical axis. The difference in height between the center and the edge of the liquid surface is: 2 R 2 / (2g) R / (2g) 2 R / g 2 R 2 / g A piece of ice with a stone embedded in it floats in a beaker containing water. When the ice melts completely, the level of water in the beaker: Falls Rises Remains same Initially rises then falls A barometer kept in an elevator reads 76 cm of Hg when the elevator is at rest. If the elevator accelerates upwards with g/4 , the new reading of the barometer will be: 60.8 cm 95 cm 76 cm 19 cm A large open tank has two small holes in its vertical wall. One hole is at a distance h from the top surface and the other is at a distance y from the bottom. If the velocity of efflux is the same for both holes, then: h = H - y h = y h = H/2 y = H/2 If the ratio of the solar constant of Earth to that of another planet is 4:1 , then the ratio of the distance of Earth from the Sun to that of the planet from the Sun is: 1:2 1:4 2:1 4:1 A liquid is kept in a cylindrical vessel which is rotated about its axis with a constant angular velocity . The pressure at a point in the liquid: Increases with the distance from the axis of rotation Decreases with the distance from the axis of rotation Remains constant Is independent of the depth A truck carrying a liquid is accelerating at 5 m/s 2 on a horizontal road. The angle made by the free surface of the liquid with the horizontal is (Take g = 10 m/s 2 ): -1 (0.5) -1 (2) -1 (0.5) -1 (0.5) A U-tube with both limbs open to the atmosphere contains mercury. When 13.6 cm of water is poured into one limb, the rise of the mercury level in the other limb is: 0.5 cm 1.0 cm 13.6 cm 1.2 cm A beaker contains water up to a height h . The pressure at the bottom of the beaker is P . If the beaker is accelerated upwards with acceleration a , the new pressure at the bottom will be: P(1 + a/g) P(1 - a/g) P(a/g) P A cylindrical tube, with its axis vertical, contains some water. When the tube is rotated about its axis with a constant angular velocity , the shape of the free surface of water is: Paraboloid Spherical Ellipsoid Plane The height to which water rises in a capillary tube is h . If the tube is taken into an elevator accelerating upwards with an acceleration a , the new height of water rise h' will be: h g/(g+a) h (g+a)/g h g/(g-a) h A cylindrical tank of height H is filled with water. A hole is made at a depth h below the free surface. The horizontal range of the water jet on the ground is maximum when: h = H/2 h = H h = H/4 h = 0 A rectangular block of mass m and area of cross-section A floats in a liquid of density . If it is given a small vertical displacement from equilibrium it undergoes oscillation with a time period T. Then:- T T 1 A T 1 T 1 m Two non-mixing liquids of densities and n (n > 1) are put in a container. The height of each liquid is h. A solid cylinder of length L and density d is put in this container. The cylinder floats with its axis vertical and length pL (p < 1) in the denser liquid. The density d is equal to :- 1 + (n + 1)p 2 + (n + 1)p 2 + (n - 1)p 1 + (n - 1)p A metal block of base area 0.2 m 2 is connected to a 0.02 kg mass via a string that passes over an ideal pulley as shown in figure. A liquid film of thickness 0.6 mm is placed between the block and the table. When released the block moves to the right with a constant speed of 0.17 m/s. The co-efficient of viscosity of the liquid is : 3.45 10 3 Pa - s 3.45 10 -2 Pa - s 3.45 10 -3 Pa - s 3.45 10 2 Pa - s A small sphere of radius 'r' falls from rest in a viscous liquid. As a result, heat is produced due to viscous force. The rate of production of heat when the sphere attains its terminal velocity, is proportional to r 5 r 2 r 3 r 4 When a block of iron floats in mercury at 0 C , a fraction k 1 of its volume is submerged, while at 60 C a fraction k 2 is submerged. If the coefficient of volume expansion of iron is Fe and that of mercury is Hg , then the ratio k 1/k 2 is: 1 + 60 Fe 1 + 60 Hg 1 + 60 Hg 1 + 60 Fe 1 + 60( Hg - Fe ) 1 + 60( Fe + Hg ) In a hydraulic press, the radii of the two pistons are 1 cm and 10 cm . If a force of 10 N is applied to the smaller piston, the force exerted by the larger piston is: 1000 N 100 N 10 N 10000 N A tank is filled with water to a height H . A small hole is made at the bottom. If the tank is placed on a trolley moving with horizontal acceleration a , the velocity of efflux will be: 2H g 2+a 2 2gH 2aH 2(g+a)H The density of water at the surface of the ocean is . If the bulk modulus of water is B , what is the density of ocean water at a depth where the pressure is nP 0 , where P 0 is the atmospheric pressure? B B - (n-1)P 0 B B + nP 0 ( 1 + nP 0 B ) 1 - nP 0/B A wooden block floating in a bucket of water has 4/5 of its volume submerged. When certain amount of oil is poured into the bucket, it is found that the block is just under the oil surface with half of its volume in water and half in oil. The density of oil is: 600 kg/m 3 800 kg/m 3 500 kg/m 3 700 kg/m 3 A solid body floats in water with k fraction of its volume submerged. At 0 C the fraction is k 0 and at t C the fraction is k t . If l is the coefficient of volume expansion of the liquid and s is that of the solid, then: k t = k 0 [1 + ( l - s)t] k t = k 0 [1 + ( s - l)t] k t = k 0 [1 + l t] k t = k 0 [1 - s t] A spherical ball of density is released from rest in a liquid of density (where > ). The initial acceleration of the ball is: g(1 - / ) g(1 - / ) g( / ) g The pressure at the bottom of a water tank of depth h is P . If the water is replaced by another liquid of density three times that of water, the pressure at the same depth h (ignoring atmospheric pressure) will be: 3P P/3 9P P The velocity of efflux of a liquid from an orifice in the bottom of a tank does NOT depend upon: Area of the orifice Density of the liquid Height of the liquid column Acceleration due to gravity Measuring Zeta potential is useful in determining which property of colloidal solution? Solubility Stability of the colloidal particles Size of the colloidal particles Viscosity A submarine is designed to withstand an absolute pressure of 100 atm. How deep can it go below the water surface? (Consider the density of water = 1000 kg m -3 , 1 atm = 1 10 5 Pa and gravitational acceleration g = 10 m/s 2 ) 9900 m 990 m 9000 m 99 m