Physics-DPP-3-Fluid Mechanics

PHYSICS Topic: FLUID MECHANICS Date: 1. A ball of mass 1 kg falls from a height of 5 m above the free surface of water. The relative density of the solid ball is s = travels a distance of 2 m under water and becomes stationary. The work done by the resistive forces of water is: (a) – 50 J (b) –20J (c) –40 J (d) –30 J 2 3 . The ball 2. There is a hole at the bottom of a cylindrical vessel. Water is filled upto a height H and water flows out in t second. If water is filled to a height 4H, it will flow out in time: t (a) 4 t (b) 2t (c) 4t (d) 2 3. A large tank is filled water (density = 103 kg/m3). A small hole is made at a depth 10 m below water surface. The range of water issuing out of the hole is R on ground. What extra pressure must be applied on the water surface, so that the range becomes 2R : (take 1 atm = 105 Pa and g = 10 m/s2) (a) 9 atm (b) 4 atm (c) 5 atm (d) 3 atm 4. A cubical block is floating in a liquid with half of its volume immersed in the liquid. when the whole system accelerated upwards with g acceleration of 3 , the fraction of volume immersed in the liquid will be: (a) 1 2 (b) 3 8 (c) 2 3 3 (d) 4 5. A wooden cube just floats inside water when a 200g mass is placed on it. When the mass is removed, the cube is 2 cm above the water level. What is the size of the cube? (a) 6 cm (b) 8 cm (c) 10 cm (d) 12 cm 6. A metal ball immersed in alcohol weighs W1 at 0ºC and W2 at 59º C. The coefficient of cubical expansion of the metal is less than that of alcohol. Assuming that the density of the metal is large compared to that of alcohol, it can be shown that: (a) W1 > W2 (b) W1 = W2 (c) W1 < W2 (d) W2 = (W1/2) 7. A uniform wooden rod of length L and specific gravity S is free to rotate in vertical plane about the end A. The rod is released in the horizontal position inside a liquid of specific gravity 1.5 S as shown in the figure. The instantaneous acceleration of the end B is: (a) g (b) g/4 (c) 3g/4 (d) 3g/8 PHYSICS Topic: FLUID MECHANICS Date: 8. Water flows from a large reservoir through a pipe of cross-sectional area S into a big stagnant lake. The level of water in the lake is at a height H1, above the end of the pipe as shown in the figure. The flow volume rate of water is: (a) S (b) S (c) S (d) S 9. A square gate of size 1m × 1m is hinged at its mid-point. A fluid of density  fills space to the left of the gate. The force F required to hold the gate stationary is: (a) ρg (b) 1 ρg (c) ρg (d) none of these 3 2 6 10. A pump is designed as a horizontal cylinder with a piston area A and an outlet orifice arranged near the axis of the cylinder. Find the velocity of outflow of liquid from pump, if the piston moves with a constant velocity under the action of a constant force F. The density of liquid  : (a) (b) (c) (d) PHYSICS Topic: FLUID MECHANICS Date: 1. (c) 2. (b) Answer Key 3. (d) 4. (a) 5. (c) 6. (c) 7. (c) 8. (b) 9. (c) 10. (b)

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