Physics-DPP-2-Fluid Mechanics

PHYSICS Topic: FLUID MECHANICS Date: 1. Pressure inside two soap bubbles are 1.01 and 1.02 atm. Ratio of their volume is : (a) 2 : 1 (b) 4 : 1 (c) 8 : 1 (d) 12 : 1 2. If cross - sectional area of limb I is A1 and that of limb II is A2, then velocity of the liquid in the tube will be, (cross - sectional area of tube is very small) : A1 (b) 2 2g (x - y) A2 (c) 1 2g (x - y) (d) none of these 3. A tank filled with water has two taps to exhaust and pour. A hollow spherical ball is half submerged in water. Through one tap, water is taken out and through another tap, a liquid of density double the density of water is poured in tank such that volume of liquid in tank remains constant. Sphere will : (a) go down (b) go up (c) maintain same height (d) sink to bottom 4. An air bubble of radius 1 mm is formed inside water at a depth 10 m below free surface (where air pressure is 105 N/m2). The pressure inside the bubble is : (a) 2. 28 × 105 N/m2 (b) 2.0028 × 105 N/m2 (c) 2.14 × 105 N/m2 (d) 2.0014 × 105 N/m2 5. If temperature increases, the surface tension of a liquid : (a) increases (b) decreases (c) remains the same (d) first increases then decreases 6. A liquid in a vertical tube. The relation between the weight of the liquid in the tube, surface tension of the liquid T and radius of the tube r is given by, if the angle of contact is zero : (a) W = πr2T (b) W = 2πrT (c) W = 2r2πT (d) W = 3 πr3T 4 7. If a water drop is kept between two glass plates, then its shape is : (a) (b) (I) (d) none of these PHYSICS Topic: FLUID MECHANICS Date: 8. A long cylindrical glass vessel has a small hole of radius r at its bottom. The depth to which the vessel can be lowered vertically in the deep water bath (surface tension T) without any water entering inside is : (a) 4 T ρrg (b) 3T ρrg (c) 2 T ρrg (d) T ρrg 9. 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 is : (a) 9.4 m (b) 4. 9 m (c) 0. 49 m (d) 0. 94 m 10. Two capillary of length L and 2 L and of radius R and 2 R are connected in series. The net rate of flow of fluid through them will be πPR 4 : (given rate of the flow through single capillary, X = (a) 8 X ` (b) 9 X 8ηL ) (c) 5 X (d) 7 X 9 8 7 5 PHYSICS Topic: FLUID MECHANICS Date: 1. (c) 2. (a) Answer Key 3. (b) 4. (d) 5. (b) 6. (b) 7. (c) 8. (c) 9. (d) 10. (a)