Tiêu đề 10. Mechanical Properties Of Fluids.pdf ✅

1. Water rises to height 'h' in capillary tube. If the length of capillary tube above the surface of water is made less than 'h', then - (1) water does not rise at all. (2) water rises upto the tip of capillary tube and then starts overflowing like a fountain. (3) water rises upto the top of capillary tube and stays there without overflowing. (4) water rises upto a point a little below the top and stays there. 2. In a capillary rise experiment, the water level rises to a height of 5 cm. If the same capillary tube is placed in water such that only 3 cm of the tube projects outside the water level, then : (1) water will begin to overflow through the capillary (2) angle of contact decreases (3) angle of contact increases (4) the meniscus completely vanishes 3 . A capillary tube of radius r is immersed in water and water rises in it to a height h. The mass of the water in the capillary tube is m. Another capillary of radius 2r is immersed in water. The mass of water that will rise in this tube i s– (1) m /2 (2) m (3) 2 m (4) 4 m 4 . There are two identical small holes of area of cross-section a on the opposite sides of a tank containing a liquid of density . The difference in height between the holes is h. Tank is resting on a smooth horizontal surface. Horizontal force which will have to be applied on the tank to keep it in equilibrium is– 5 . An ornament weighs 10 g in air and 6 g in water. Density of material of ornament is 20 g cc .The volume of cavity in ornament is– (1) zero (2) 3. 5 cc (3) 4 cc (4) 0. 5 cc 6. 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=10.5kg/m) of the same size in the same liquid. (1) 0.4 m/s (2) 0.133 m/s (3) 0.1 m/s (4) 0.2 m/s 7. Work done in increasing the size of a soap bubble from a radius of 3 cm to 5cm is nearly (Surface tension of soap solution = 0.03 Nm): (1)2  mJ (2) 0.4  mJ (3) 4  mJ (4) 0.2  mJ 8. When 106 smaller drops of a liquid are combined to form a new bigger drop, then its- (1) density will decrease (2) density will increase (3) temperature will increase (4) temperature will decrease 9. A wooden piece floats half submerged in a tub of water. If the system is transferred to a lift ascending with acceleration the wooden piece will : (1) Sink a little more (2) Rise a little (3) Remain half submerged (4) Sink to the bottom A. If both Assertion & Reason are True & the Reason is a correct explanation of the Assertion. B. If both Assertion & Reason are True but Reasonis not a correct explanation of the Assertion. C. If Assertion is True but the Reason is False. D. If both Assertion & Reason are False. 10. Assertion :- Buoyancy is a conservative force. Reason :- According to Archimedes principlebuoyancy is equal to the weight of displaced liquid. (1) A (2) B (3) C (4) D 11. Assertion :- A bubble comes from the bottom ofa lake to the top its radius increases. Reason :- Its radius increases. (1) A (2) B (3) C (4) D 12. A liquid drop at temperature t, isolated from its surroundings, breaks into a number of droplets. The temperature of the droplets will be (1) Equal to t (2) Greater than t (3) Less than t Mechanical Properties of Fluids
(4) Either (1), (2) or (3) depending on the surface tension of the liquid. 13. Two soap bubbles with radii r1and r2(r1> r2) come in contact. Their common surface has a radius of curvature r 14. A beaker containing a liquid of density  moves up with an acceleration a; the pressure due to the liquid at a depth h below the free surface of the liquid is 15. A U-tube containing a liquid moves with a horizontal acceleration a along a direction joining the two vertical limbs. The separation between these limbs is d. The difference in their liquid levels is (1) ad/g (2) 2da/g (3) da/2g (4) d tan (a/g) 16. A vertical glass capillary tube open at both ends contains some water. Which of the following shapes may be taken by the water in the tube? 17. The area of cross-section of the wider tube shown in the figure is 800 cm2 . If a mass of 12 kg is placed on the massless piston, the difference in the heights h in the level of water in two tubes. (1) 10 cm (2) 6 cm (3) 15 cm (4) 2 cm 18. The surface tension of soap solution is 0.03 N/m. The work done in blowing to form a soap bubble of surface area 40 cm2 is : (1) 1.2 × 10–4 J (2) 2.4 × 10–4 J (3) 12 × 10–4 J (4) 24× 10–4 J 19. Pressure at the bottom of a tank of water is 3P, where P is atmospheric pressure. If the water is drawn out till the level of water is lowered by one fifth, then the pressure at the bottom of the tank is :- (1) 2P (2) 13P/5 (3) 8P/5 (4) 4P/5 20. The diagram (figure) shows a venture meter, through which water is flowing. The speed of water at X is 2 cm/s. The speed of water at Y (taking g = 1000 cm/s2 ) is :– (1) 23 cm/s (2) 32 cm/s (3) 101 cm/s (4) 1024 cm/s 21. A liquid drop of diameter D breaks into 27 tiny drops. The change in energy is :– (1) 2  TD2 (2) 4  TD2 (3)  TD2 (4) None of these 22. A wooden cube first floats inside water when a 200 g mass is placed on it. When the mass is removed the cube is 2 cm above water level. The side of cube is :– (1) 5 cm (2) 10 cm (3) 15 cm (4) 20 cm 23. Two identical cylindrical vessels with their bases at the same level, each contains a liquid of density  . The height of the liquid in one vessel is h1 and that in the other h2. The area of either bases is A. The work done by the gravity in equalizing the levels when the vessels are interconnected is :- 24. A jar is filled with two non-mixing liquids 1 and 2 having densities 1 and 2 , respectively. A solid ball, made of a material of density 3 , is dropped in the jar. It comes to equilibrium in the position shown in the figure. Which of the following is true for 1 , 2 & 3 ?
25. A homogeneous solid cylinder of length L (L < H/2), cross–sectional area A/5 is immersed such that it floats with its axis vertical at the liquid–liquid interface with length L/4 in the denser liquid as shown in the figure. The lower density liquid is open to atmosphere having pressure P. Then, density D of solid cylinder is given by :– 26. A piece of ice is floating in a jar containing water. When the ice melts, then the level of water : (1) Rises (2) Falls (3) Remains unchanged (4) Changes erratically 27. A large open tank has two holes in the wall. One is a square hole of side L at a depth y from the top and the other is a circular hole of radius R at a depth 4y from the top. When the tank is completely filled with water, the quantities of water flowing out per second from both the holes are same. Then, R is equal to :– 28. The flow speeds of air on the lower and upper surfaces of the wing of an aero plane are v and 2 v respectively. The density of air is  and surface area of wing is A. The dynamic lift on the 2 wing is : 29. If T be the surface tension, the amount of work done in blowing a soap bubble from a diameter d to diameter D is : (1)  (D2 – d 2 )T (2) 2  (D2 – d 2 )T (3) 4  (D2 – d 2 )T (4) 8  (D2 – d 2 )T 30. When a capillary tube is dipped into a tub containing mercury then the mercury level in the capillary goes down because the pressure just below the meniscus is : (1) zero (2) equal to atmospheric pressure (3) less than atmospheric pressure (4) more than the atomospheric pressure 31. Water falls from a tap, down the stream line : (1) Area decreases (2) Area increases (3) Velocity remains same (4) Area remains same 32. In a U-tube experiment, a column AB of water is balanced by a column ‘CD’ of oil, as shown in the figure. Then the relative density of oil is:- (1) 2 1 h h (2) 1 2 h h (3) ( 1 2 ) 1 h h h − (4) ( ) 2 1 2 h h h +
33. Two capillaries of same material but of different radii are dipped in a liquid. In one of the capillary the liquid rises to a height of 22 cm and in other to 66 cm. The ratio of their radii is :- (1) 9 : 1 (2) 1 : 9 (3) 3 : 1 (4) 1 : 3 34. In making an alloy, a substance of specific gravitys1 and mass m1 is mixed with another substance of specific gravity s2 and mass m2; then the specific gravity of the alloy is :- (1) 1 2 1 2 m m s s   +     + (2) 1 2 1 2 s s m m       + (3) ( ) 1 2 1 1 2 2 / m m m s m s   +   +   (4) ( 1 1 2 2 ) 1 2 m s m s / m m   +     + 35. Block A in the figure shown here hangs by a cord from dynamometer (spring balance) D1 and is submerged in a liquid C contained in a beaker B. The mass of the beaker is 1 kg and the mass of liquid is 1.5 kg. The readings of dynamometersD1 and D2 are 2.5 kg and 7.5 kg respectively. What will be the readings of D1 and D2 if block A is pulled up out of liquid :- (1) D1 will read 5 kg and D2 will also read5kg (2) D1 will read 7.5 kg and D2 will read2.5kg (3) D1 will read 2.5 kg and D2 will read7.5kg (4) D1 will read 10 kg and D2 will read 2.5 kg 36. Water is flowing continuously from a tap having an internal diameter 8  10–3 m. The water velocity as it leaves the tap is 0.4 ms–1 . The diameter of the water stream at a distance 2  10–1 m below the tap is close to :- (1) 5.0  10–3 m (2) 7.5  10–3 m (3) 9.6  10–3 m (4) 3.6  10–3 m 37. A large number of liquid drops each of radius r coalesce to form a single drop of radius R. The energy released in the process is converted into the kinetic energy of the big drop so formed. The speed of the big drop is : (given surface tension of liquid is T, density of liquid is  ) :- (1) T 1 1  r R     −   (2) 2 1 1 T  r R     −   (3) 4 1 1 T  r R     −   (4) 6 1 1 T  r R     −   38. A certain number of spherical drops of a liquid of radius 'r' coalesce to form a single drop of radius 'R' and volume 'V'. If 'T' is the surface tension of the liquid, then : (1) energy 1 1 4VT r R   = −     is released (2) energy 1 1 3VT r R   = +     is absorbed (3) energy = 3VT 1 1 3VT r R   = −     is released (4) Energy is neither released nor absorbed 39. Water rises in a capillary upto a height of 4 cm. If it is tilted to 30o from the vertical, then the length of water column in it will be - (1) 8 3 cm (2) 8 3 cm (3) 4 cm (4) 2 cm