HSC Science (Electronics) 12th Standard Board Exam - Maharashtra State Board Question Bank Solutions

Multiple Choice Question.

Two hailstones with radii in the ratio of 1:4 fall from a great height through the atmosphere. Then the ratio of their terminal velocities is

Why does velocity increase when water flowing in broader pipe enters a narrow pipe?

With what terminal velocity will an air bubble 0.4 mm in diameter rise in a liquid of viscosity 0.1 Ns/m² and specific gravity 0.9? Density of air is 1.29 kg/m³.

Calculate the viscous force acting on a raindrop of diameter 1 mm, falling with a uniform velocity of 2 m/s through air. The coefficient of viscosity of air is 1.8 × 10^-5 Ns/m².

A horizontal force of 1 N is required to move a metal plate of area 10^-2 m² with a velocity of 2 × 10^-2 m/s, when it rests on a layer of oil 1.5 × 10^-3 m thick. Find the coefficient of viscosity of oil.

Two stones with radii 1:2 fall from a great height through the atmosphere. Their terminal velocities are in the ratio ______ 

What is the net weight of a body when it falls with terminal velocity through a viscous medium?

A square metal plate of area 100 cm² moves parallel to another plate with a velocity of 10 cm/s, both plates immersed in water. If the viscous force is 200 dyne and the viscosity of water is 0.01 poise, what is the distance between them?   

The relative velocity between two parallel layers of water is 8 cm/s and the perpendicular distance between them is 0.1 cm. Calculate the velocity gradient. 

A raindrop of radius 0.3 mm falls through the air with a terminal velocity of 1 m/s. The viscosity of air is 18 x 10⁻⁶ Ns /m². Find the viscous force on the raindrop.  

State the formula for critical velocity in terms of Reynold's number for a flow of a fluid.

What are the two main causes of turbulent flow?

Define the coefficient of viscosity.

State the formula and S.I. units of coefficient of viscosity.

Define velocity gradient.

An incompressible liquid is flowing through a uniform cross-sectional tube with a velocity 12 cm/ s. If the thickness of liquid layer is 0.8 cm, what is the velocity gradient of that flow of liquid?

State and explain Newton's law of viscosity.

A force of 0.01 N is required to move a flat glass plate of area of 10 cm² with a uniform velocity of 1 cm/ s over the surface of a liquid 2 mm thick. If the coefficient of viscosity of the liquid is 20 poise, the velocity gradient in the liquid layer is ______.

The dimensions of coefficient of viscosity are ______.

A water pipe with diameter of 5.0 cm is connected to another pipe of diameter 2.5 cm. How would the speeds of the water flow compare?