Tiêu đề 10.MECHANICAL PROPERTIES OF FLUIDS - Questions.pdf ✅

10.MECHANICAL PROPERTIES OF FLUIDS (1.)A uniform tapering vessel shown in figure is filled with liquid of density 900 kgm−3 . The force that acts on the base of the vessel due to liquid is (take g =10 ms −2 ) (a.) 3. 6 N (b.) 7.2 N (c.) 9. 0 N (d.) 12. 0 N (2.)A cylindrical tank has a hole of 1 cm2 in its bottom. If the water is allowed to flow into the tank from a tube above it at the rate of 70 cm3 /sec. then the maximum height up to which water can rise in the tank is (a.) 2.5 cm (b.) 5 cm (c.) 10 cm (d.) 0.25 cm (3.)Aerofils are so designed that the speed of air (a.) On top side is more than on lower side (b.) On top side is less than on lower side (c.) Is same on both sides (d.) Is turbulent (4.)A liquid flows through a pipe of non-uniform cross-section. If A1 and A2 are the cross-sectional area of the pipe at two points, the ratio of velocities of the liquid at these points will be (a.) A1A2 (b.) A1 A2 (c.) A2 A1 (d.) 1 A1A2 (5.)A viscous fluid is flowing through a cylindrical tube. The velocity distribution of the fluid is best represented by the diagram (a.) (b.) (c.) (d.) None of these (6.)A solid sphere of density η(> 1) times lighter than water is suspended in a water tank by a string tied to its base as shown in fig. If the mass of the sphere is m then the tension in the string is given by (a.) ( η−1 η ) mg (b.) ηmg (c.) mg η−1 (d.) (η − 1)mg (7.)Two solid pieces, one of steel and the other of aluminum when immersed completely in water have equal weights. When the solid pieces are weighed in air (a.) the weight of aluminium is half the weight of steel (b.) steel piece will weigh more (c.) they have the same weight (d.) aluminium piece will weigh more (8.)The relative velocity of two parallel layers of water is 8 cms −1 . If the perpendicular distance between the layers is 0.1 cm, then velocity gradient will be (a.) 40 s −1 (b.) 50 s −1 (c.) 60 s −1 (d.) 80 s −1 (9.)A capillary tube of radius R and length L is connected in series with another tube of radius R/2 and lengthL/4. If the pressure difference across the two tubes taken together is p, then the ratio of pressure difference across the first tube to that across the second tube is (a.) 1 : 4 (b.) 1 : 1 (c.) 4 : 1 (d.) 2 : 1 (10.)Radius of an air bubble at the bottom of the lake is r and it becomes 2rwhen the air bubble rises
to the top surface of the lake. If ρ cm of water be the atmospheric pressure, then the depth of lake is (a.) 2p (b.) 8p (c.) 4p (d.) 7p (11.)Water is flowing in a pipe of diameter 4 cm with a velocity 3 ms−1 . The water then enters in to a pipe of diameter 2 cm. the velocity of water in the other pipe is (a.) 3 ms−1 (b.) 6 ms−1 (c.) 12 ms−1 (d.) 8 ms−1 (12.)A mercury drop of radius 1 cm is broken into 106 droplets of equal size. The work done is (S = 35 × 10−2 Nm−1 ) (a.) 4.35 × 10−2 J (b.) 4.35 × 10−3 J (c.) 4.35 × 10−6 J (d.) 4.35 × 10−8 J (13.)A liquid X of density 3.36 g cm−3 is poured in a U-tube, which contains Hg. Another liquid Y is poured in left arm with height 8 cm, upper levels of X and Y are same. What is density of Y? (a.) 0.8 gcc−1 (b.) 1.2 gcc−1 (c.) 1.4 gcc−1 (d.) 1.6gcc−1 (14.)According to Bernoulli’s equation P ρg + h + 1 2 v 2 g = constant The terms A, B and C are generally called respectively (a.) Gravitational head, pressure head and velocity head (b.) Gravity, gravitational head and velocity head (c.) Pressure head, gravitational head and velocity head (d.) Gravity, pressure and velocity head (15.)The onset of turbulence in a liquid is determined by (a.) Pascal’s law (b.) Magnus effect (c.) Reynold’s number (d.) Bernoulli’s principle (16.)Two stretched membranes of area 2 cm2 and 3 cm2 are placed in a liquid at the same depth. The ratio of pressure on them is (a.) 1 : 1 (b.) 2 : 3 (c.) 3 : 2 (d.) 2 2 ∶ 3 2 (17.)An ice block contains a glass ball when the ice melts within the water containing vessel, the level of water (a.) Rises (b.) Falls (c.) Unchanged (d.) First rises and then falls (18.)A beaker of radius 15 cm is filled with a liquid of surface tension 0.75 Nm−1 . Force across an imaginary diameter on the surface of the liquid is (a.) 0.075 N (b.) 1.5 × 10−2 N (c.) 0.225 N (d.) 2.25 × 10−2 N (19.)A block of wood weighs 4N in air and 3N when immersed in a liquid. The buoyant force in newton is (a.) Zero (b.) 1 (c.) 3/4 (d.) 4/3 (20.)From the adjacent figure, the correct observation is (a.) the pressure on the bottom of the tank A is greater than at the bottom of B (b.) the pressure on the bottom of the tank A smaller than at the bottom of B (c.) the pressure depends on the shape of the container (d.) the pressure on the bottom of A and B is the same (21.)A container of height 10 m which is open at the top, has water to its full height. Two small openings are made on the walls of the container one exactly at the middle and the other at the bottom. The ratio of the velocities with which water comes out from the middle and the bottom region respectively is (a.) 2 (b.) 1 2 (c.) √2 (d.) 1 √2
(22.)The excess pressure inside a spherical drop of radius r of a liquid of surface tension T is (a.) Directly proportional to r and inversely proportional to T (b.) Directly proportional to T and inversely proportional to r (c.) Directly proportional to the product of T and r (d.) Inversely proportional to the product of T and r (23.)Two communicating vessels contain mercury. The diameter of one vessel is n times larger than the diameter of the other. A column of water of height h is poured into the left vessel. The mercury level will rise in the right-hand vessel (s = relative density of mercury and ρ = density of water) by (a.) n 2h (n+1)2s (b.) h (n2+1)s (c.) h (n+1)2s (d.) h n2s (24.)If two soap bubble of different radii are connected by a tube (a.) Air flows from the bigger bubble to the smaller bubble till the sizes become equal (b.) Air flows from bigger bubble to the smaller bubble till the sizes are interchanged (c.) Air flows from the smaller bubble to the bigger (d.) There is no flow of air (25.)10 cm long wire is placed horizontally on the surface of water and is gently pulled up with a force of 2 × 10−2 N to keep the wire in equilibrium. The surface tension of water in Nm−1 is (a.) 0.002 (b.) 0.001 (c.) 0.2 (d.) 0.1 (26.)The pressure inside two soap bubble is 1.01 and 1.02 atm respectively. The ratio of their respective volume is (a.) 2 (b.) 4 (c.) 6 (d.) 8 (27.)Two tubes A and B are in series. Radius of A is R and that of B is 2R. If water flows through A with velocity then velocity of water through B is (a.) v 2 (b.) v (c.) v 4 (d.) v 8 (28.)The surface tension of soap solution is 0.03 Nm−1 . the work done in blowing to from a soap bubble of surface area 40 cm2 , (in J), is (a.) 1.2 × 10−4 (b.) 2.4 × 10−4 (c.) 12 × 10−4 (d.) 24 × 10−4 (29.)Figure shows the vertical cross section of a vessel filled with a liquid of densityρ. The normal thrust per unit area on the walls of the vessel at point P, as shown will be (a.) h ρ g (b.) H ρ g (c.) (H − h)ρ g (d.) (H − h)ρ g cos θ (30.)Spherical ball of radius R are falling in a viscous fluid of viscosity ɳ with a velocity v. The retarding viscous force acting on the spherical ball is (a.) directly proportional to R but inversely proportional tov (b.) directly proportional to both radius R and velocity v (c.) inversely proportional to both radius R and velocityv (d.) inversely proportional to R but directly proportional to velocity v (31.)A candle of diameter d is floating on a liquid in a cylindrical container of diameter D(D > > d) as shown in figure. If it is burning at the rate of 2cm/hour then the top of the candle will (a.) Remain at the same height (b.) Fall at the rate of 1 cm/hour (c.) Fall at the rate of 2 cm/hour (d.) Go up the rate of 1 cm/hour (32.)A cubical block of wood 10 cm on a side floats at the interface between oil and water with its lower surface horizontal and 4 cm below the h Water Mercury
interface. The density of oil is 0.6gcm−3 . The mass of block is (a.) 706 g (b.) 607 g (c.) 760 g (d.) 670 g (33.)A wooden ball of density D is immersed in water of density d to a depth h below the surface of water and then released. Upto what height will then ball jump out of water? (a.) d D h (b.) ( d D − 1) h (c.) h (d.) Zero (34.)A wooden block of volume 1000 cm3 is suspended from a spring balance. It weighs 12 N in air. It is suspended in water such that half of the block is below the surface of water. The reading of the spring balance is (a.) 10 N (b.) 9 N (c.) 8 N (d.) 7 N (35.)Ice pieces are floating in beaker A containing water also in a beaker B containing miscible liquid of specific gravity 1.2. When ice melts, the level of (a.) water increases in A (b.) water decreases in A (c.) liquid in B decreases (d.) liquid in B increases (36.)A vessel, whose bottom has round holes with diameter 0.1 mm is filled with water. The maximum height upto which water can be filled without leakage is (Surface tension = 75 dyne cm−1 and g = 1000 cms −2 ) (a.) 100 cm (b.) 75 cm (c.) 60 cm (d.) 30 cm (37.)On the surface of the liquid in equilibrium, molecules of the liquid possess (a.) maximum potential energy (b.) maximum potential energy (c.) maximum kinetic energy (d.) minimum kinetic energy (38.)The fraction of a floating object of volume V0 and density d0 above the surface of a liquid of density d will be (a.) d0 d (b.) dd0 d+d0 (c.) d−d0 d (d.) dd0 d−d0 (39.)Two capillaries of same length and radii in the ratio 1:2 are connected in series. A liquid flows through them in streamlined condition. If the pressure across the two extreme ends of the combination is 1 m of water, the pressure difference across first capillary of (a.) 9.4 m (b.) 4.9 m (c.) 0.49 m (d.) 0.94 m (40.)To get the maximum flight, a ball must be thrown as (a.) (b.) (c.) (d.) None of these (41.)Water stands at level A in the arrangement shown in the figure. What will happen if a jet of air is gently blown into the horizontal tube in the direction shown in the figure? (a.) Water will rise above A in the capillary tube (b.) Water will fall below A in the capillary tube (c.) There will be no effect on the level of water in the capillary tube (d.) Air will emerge from end B in the form of bubbles (42.)An incompressible fluid flows steadily through a cylindrical pipe which has radius 2r at point A and radius r at B further along the flow direction. If the velocity at point A is v, its velocity at point B is (a.) 2v (b.) v (c.) v/2