EASY
Earn 100

A parachute descend slowly because it has a large surface area coming down fast so the air which collides with that surface exerts force on that surface in _____ direction so its speed of coming down also gets reduced.

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Important Questions on Mechanical Properties of Fluids
MEDIUM
A solid sphere, of radius R acquires a terminal velocity when falling (due to gravity) through a viscous fluid having a coefficient of viscosity The sphere is broken into 27 identical solid spheres. If each of these spheres acquires a terminal velocity, when falling through the same fluid, the ratio equals:

MEDIUM
Two solid spheres of the same metal but of mass and fall simultaneously in a viscous liquid. The ratio of terminal velocity of the second sphere to that of the first sphere is

MEDIUM
Which of the following option correctly describes the variation of the speed and acceleration 'a' of a point mass falling vertically in a viscous medium that applies a force , where 'k' is a constant, on the body? (Graphs are schematic and not drown to scale)

MEDIUM
A rain drop of radius has a terminal velocity in air of . The viscosity of air is poise. The viscous force on it is

HARD
Two tubes of radii and and lengths and respectively, are connected in series and a liquid flows through each of them in stream line conditions. and are pressure differences across the two tubes. If is and is then the radius will be equal to :

MEDIUM
If a ball of steel attains a terminal velocity of when falling in a tank of water (coefficient of viscosity then its terminal velocity in glycerine
would be nearly

MEDIUM
A small sphere of mass m is dropped from a great height. After it has fallen 100 m, it has attained its terminal velocity and continues to fall at that speed. The work done by air friction against the sphere during the first 100 m of fall is

MEDIUM
The terminal speed of a sphere of gold is in a viscous liquid . Then the terminal speed of a sphere of silver of the same size in the same liquid is

MEDIUM
Eight equal drops of water are falling through air with a steady velocity of if the drops combine to form a single drop big size, then the terminal velocity of this big drop is

HARD
A solid sphere moves at a terminal velocity of in air at a place where . The sphere is taken in a gravity free hall having air at the same pressure and pushed down at a speed of .

MEDIUM
In Millikan's oil drop experiment, an oil drop of mass is balanced by an electric field of . The charge in coulomb on the drop is (assuming )

MEDIUM
A spherical ball of radius and density falls freely under gravity through a distance before entering a tank of water. If after entering the water the velocity of the ball does not change, find . The viscosity of water is .

MEDIUM
Spherical ball of radius are falling in a viscous fluid of viscosity ɳ with a velocity . The retarding viscous force acting on the spherical ball is

MEDIUM
A tiny spherical oil drop carrying a net charge q is balanced in still air with a vertical uniform electric field of strength . When the field is switched off, the drop is observed to fall with terminal velocity . Given , viscosity of the air and the density of oil , the magnitude of is

MEDIUM
An iron sphere of mass kg falls through a viscous liquid with terminal velocity . The terminal velocity of another iron sphere of mass kg is

HARD
Two solid spheres and of equal volumes but of different densities and are connected by a string. They are fully immersed in a fluid of density . They get arranged into an equilibrium state as shown in the figure with a tension in the string. The arrangement is possible only if:

MEDIUM
What will be the approximate terminal velocity of a rain drop of diameter , when density of rain water and the coefficient of viscosity of air ?

EASY
In Millikan's oil drop experiment a drop of charge and radius is kept constant between two plates of potential difference of . Then charge on other drop of radius which is kept constant with a potential difference of is

MEDIUM
Eight drops of a density and each of radius are falling through air with a constant velocity . When the eight drops coalesce to from a single drop the terminal velocity of the new drop will be

MEDIUM
A sphere of mass and radius is dropped in a liquid, then terminal velocity of sphere is proportional to
