Physics - Fluid Mechanics Questions and Answer >> 1 2 3 4 5 Next >> Page 1 of 8 pages (36 Objective Questions) 1. A beaker containing a liquid is kept inside a big closed jar. If the air inside the jar is continuously pumped out, the pressure in the liquid near the bottom of the liquid will Increases Remain constant Decreases First decrease and then increase Answer: Decreases Explanation: Total pressure at (near) bottom of the liquid P = P₀ + hρg As air is continuously pumped out from jar (container), P₀ decreases and hence P decreases. 2. Spherical balls of radius r are falling in a viscous fluid of viscosity η with a velocity v. The retarding viscous force acting on the spherical ball is. Inversely proportional to r but directly proportional to velocity v Inversely proportional to both radius r and velocity v Directly proportional to both radius r and velocity v Directly proportional to r but inversely proportional to v Answer: Directly proportional to both radius r and velocity v Explanation: F = 6πηrv₁ 3. A body is just floating on the surface of a liquid. The density of the body is same as that of the liquid. The body is slightly pushed down. What will happen to the body . It will slowly come back to its earlier position It will sink It will remain submerged, where it is left It will come out violently Answer: It will remain submerged, where it is left Explanation: Help us to explain question in discussion 4. Two pieces of metal when immersed in a liquid have equal upthrust on them; then Both pieces must have equal weights Both pieces must have equal volumes Both pieces must have equal densities Both are floating to the same depth Answer: Both pieces must have equal volumes Explanation: Since, up thrust (F) = Vσg i.e. F ∝ V 5. A concrete sphere of radius R has a cavity of radius r which is packed with sawdust. The specific gravities of concrete and sawdust are respectively 2.4 and 0.3 for this sphere to float with its entire volume submerged under water. Ratio of mass of concrete to mass of sawdust will be . 8 3 4 Zero Answer: 4 Explanation: Help us to explain question in discussion \
Posted on: Fri, 22 Aug 2014 13:28:34 +0000
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