Free NEET Physics multiple-choice questions on Viscosity & Stokes' Law. Attempt each question and reveal the answer with a full explanation.
A spherical ball of radius r is falling through a viscous medium of viscosity with a terminal velocity v . Another ball of radius 2r and of the same material falls through the same medium. Its terminal velocity will be: 4v 2v v/2 v/4 A solid sphere is sinking in a viscous liquid with constant velocity. The net force acting on the sphere is: Zero Equal to the weight of the sphere Equal to the buoyant force Equal to the viscous drag When the velocity of a liquid flowing in a pipe exceeds the critical velocity, the flow becomes: Turbulent Streamline Steady Laminar A square plate of side l moves parallel to another plate with velocity v , with a liquid of viscosity and thickness d between them. The viscous force is: l 2 v / d l v / d l 2 v d l v / d 2 The magnitude of the force F required to maintain a velocity v for a plate of area A moving over a fixed plate with a liquid of viscosity and thickness d in between is: Av/d v/Ad Ad/v v 2/Ad A spherical ball is dropped in a long column of a highly viscous liquid. The curve in the graph shown, which represents the speed of the ball ( v ) as a function of time ( t ) is B C D A The venturi-meter works on Huygen’s principle Bernoulli’s principle The principle of parallel axes The principle of perpendicular axes The viscosity of a liquid and the viscosity of a gas with an increase in temperature. Decreases, increases Increases, decreases Increases, increases Decreases, decreases A square metal plate of side 10 cm is moving parallel to another identical plate with a velocity of 0.1 m/s and both are immersed in water. If the viscous force is 2 10 -3 N and the coefficient of viscosity of water is 10 -3 Pa s , what is the distance between the plates? 0.5 mm 0.05 mm 5 mm 1 mm The viscosity of a liquid with pressure, while the viscosity of water with pressure for values up to a few hundred atmospheres. Increases, decreases Increases, increases Decreases, increases Decreases, decreases A small air bubble of radius r rises through a liquid of density and viscosity . Neglecting the density of air, the terminal velocity of the bubble is: 2r 2 g / (9 ) r 2 g / (9 ) 4r 2 g / (9 ) 2r 2 g / (3 ) A small spherical ball of radius r is falling through a column of viscous liquid of coefficient of viscosity . If the ball attains terminal velocity v , the viscous force F acting on the ball is proportional to: r v r 2 v 2 r v r v 2 A solid sphere falls with a terminal velocity of 10 cm/s in a liquid. If the sphere is cut into 8 identical smaller spheres, then the terminal velocity of each smaller sphere in the same liquid will be: 2.5 cm/s 5 cm/s 1.25 cm/s 10 cm/s A small hole of area of cross-section 2 mm 2 is present near the bottom of a fully filled open tank of height 2 m . Taking g = 10 m/s 2 , the rate of flow of water through the open hole would be nearly 6.4 10 -6 m 3/ s 12.6 10 -6 m 3/ s 8.9 10 -6 m 3/ s 2.23 10 -6 m 3/ s The velocity of a small ball of mass M and density d , when dropped in a container filled with glycerine becomes constant after some time. If the density of glycerine is d 2 , then the viscous force acting on the ball will be Mg 3 2 Mg 2Mg Mg 2 A small sphere of radius r falls from rest in a viscous liquid. As a result, heat is produced due to viscous force. The rate of production of heat when the sphere attains its terminal velocity, is proportional to: r 5 r 2 r 3 r 4 The terminal velocity of a copper ball of radius 2 mm falling through a tank of oil at 20 C is 6.5 cm/s . Compute the viscosity of the oil at 20 C . Density of oil is 1.5 10 3 kg/m 3 , density of copper is 8.9 10 3 kg/m 3 . 0.99 kg m -1 s -1 0.50 kg m -1 s -1 1.50 kg m -1 s -1 2.10 kg m -1 s -1 A small sphere of radius r falls from rest in a viscous liquid. Due to friction, heat is produced. The rate of production of heat when the sphere attains its terminal velocity is proportional to: r 5 r 2 r 3 r 4 A rain drop of radius 0.3 mm has a terminal velocity in air of 1 m/s . The viscous force on it is: (Viscosity of air is 18 10 -5 poise ) 1.01 10 -7 N 1.01 10 -9 N 2.05 10 -6 N 1.01 10 -4 N In the measurement of viscosity of liquids using terminal velocity experiment, spherical balls of same radius but having different densities are used. The variation of the terminal velocity ( v ) with the ratio of density of spherical ball ( ) to density of the liquid ( ) is best represented by: Graph (1) Graph (2) Graph (3) Graph (4) Which of the following is the correct unit for the coefficient of viscosity? kg m -1 s -1 kg m s -1 kg m -2 s -1 kg m s -2 The coefficient of viscosity of a liquid depends on: Temperature Pressure only Area of cross-section of flow Velocity gradient The Reynold's number of a flow is 1000 . The nature of flow is: Laminar Turbulent Unsteady Transitional What is the dimensions of the coefficient of viscosity? [M 1 L -1 T -1 ] [M 1 L 1 T -1 ] [M 1 L -1 T -2 ] [M 1 L -2 T -1 ] Two spheres of the same material but radii r and 2r are dropped into a long column of a viscous liquid. The ratio of their terminal velocities will be: 1 : 4 1 : 2 1 : 8 1 : 1 Viscosity of a liquid with the addition of soluble impurities like salt. Increases Decreases Remains constant First increases then decreases A steel ball is falling through a viscous liquid. The graph of its velocity versus time will show: Velocity increasing and then becoming constant Velocity increasing linearly Velocity decreasing linearly Velocity remaining constant from the start