A ball of density σ and radius r is dropped on the surface of a liquid of density ρ from certain height. If speed of ball does not change even on entering in liquid and viscosity of liquid is η, then the height from which ball dropped is
2gσ-ρrη2
2g(σ-ρ)2r29η
2(σ-ρ)gr29η
2g(σ-ρ)r29η2
Viscous drag force depends on
Size of body
Velocity with which it moves
Viscosity of fluid
All of these
The terminal velocity of a small sized spherical body of radius r falling vertically in a viscous liquid is related to radius r as-
v∝1r2
v∝r2
v∝1r
v∝r
On putting a capillary tube in a pot filled with water, the level of water rises upto a height of 4 cm in the tube. If a tube of half the diameter is used instead, the water will rise to a height nerly
2 cm
4 cm
8 cm
11 cm
Soap helps in cleaning clothes, because
It attracts the dirt particles
It decreases the surface tension of water
It increases the cohesive force between water molecules
It increases the angle of contact
On increasing temperature of a liquid, its surface tension generally
Increases
Decreases
Remains constant
First increases and then decreases
The raincoats are made water proof by coating it with a material, which
Absorb water
Increase surface tension of water
Increase the angle of contact
Decreases the density of water
An iron needle slowly placed on the surface of water floats because
It displaces water more than its weight
The density of material of needle is less than that of water
Of surface tension
Of its shape
Two water droplets merge with each other to form a larger droplet. In this process
Energy is liberated
Energy is absorbed
Energy is neither liberated nor absorbed
Some mass is converted into energy
The radius of a soap bubble is r. The surface tension of soap solution is 'S'. Keeping temperature constant, the radius of the soap bubble is soubled. The energy necessary for this will be
24 πr2S
8 πr2S
16 πr2S
12 πr2S
The surface tension of a liquid is 5 N/m. If a film is held on a ring of area 0.02 m2, its surface energy is about
5×10-2 J
2.5×10-2 J
2×10-1 J
3×10-1 J
Two soap bubbles having radii 3 cm and 4 cm in vacuum, coalesce under isothermal conditions. The radius of the new bubble is
1 cm
5 cm
7 cm
3.5 cm
The work done to break a spherical drop of radius R in n drops of equal size is proportional to
1n2/3-1
1n1/3-1
n1/3-1
n4/3-1
The kerosene oil rises up in the wick of a lamp
Due to high surface tension of coil
Because the wick attracts the oil
Because the wick decreases the surface tension of oil
Due to capillaries formed in the wick
Ploughing help to retain water by soil
By creating capillaries
By breaking capillaries
By turning the soil upside down
None of these
A capillary tube of radius r is immersed in a liquid and mass of liquid, which rises up in it is M. If the radius of tube is doubled, then the mass of liquid which will rise in capillary tube will be
2 M
M
M/M
M/4
A massless inextensible string in the form of a loop is placed on a horizontal film of soap solution of surface tension T. If film is pierced inside the loop and it converts into a circular loop of diameter d, then the tension produced in the string is
Td
πTd
πd2T
πd2T4
A tank is filled with water to a height H. A hole is made in one of the walls at a depht D below the water surface. The distance x from the foot of the wall at which the stream of water coming out the tank strikes the ground is given by
x=2[D(H-D)]1/2
x=2(gD)1/2
x=2[D(H+D)]1/2
In streamline flow of liquid, the total energy of liquid is constant at:
all points
inner points
outer points
none of the above
A good lubricant should have:
high viscosity
low viscosity
moderate viscosity
high density
Water is flowing in a horizontal pipe of non-uniform cross-section. At the most contracted place of the pipe:
velocity of water will be maximum and pressure minimum.
pressure of water will be maximum and velocity minimum.
both pressure and velocity of water will be maximum.
both pressure and velocity of water will be minimum.
Bernoulli's theorem is based upon:
Faraday's law
Conservation of energy
Conservation mass
A tank has an orifice near its bottom. The volume of the liquid flowing per second out of the orifice does not depend upon:
the area of the orifice.
the height of the liquid level above the orifice.
the density of the liquid.
acceleration due to gravity.
Pressure is a scalar quantity because:
it is the ratio of force to area and both force and area are vectors.
it is the ratio of the magnitude of the force to area.
it is the ratio of the component of the force normal to the area.
it does not depend on the size of the area chosen.
Along a streamline:
the velocity of a fluid particle remains constant.
the velocity of all fluid particles crossing a given position is constant.
the velocity of all fluid particles at a given instant is constant.
the speed of a fluid particle remains constant.
With increase in temperature, the viscosity of:
gases decreases.
liquids increases.
gases increases.
none of these.
The angle of contact at the interface of water-glass is 0o, Ethylalcohol-glass is 0o, Mercury-glass is 140o and Methyliodideglass is 30o. A glass capillary is put in a trough containing one of these four liquids. It is observed that the meniscus is convex. The liquid in the trough is:
Water
Ethyl alcohol
Mercury
Methyl iodides
Which of the following diagrams does not represent a streamline flow?
Q. 3 Along a streamline,
() the velocity of a fluid particle remains constant.
() the velocity of all fluid particles crossing a given position is constant.
() the velocity of all fluid particles at a given instant is constant.
() the speed of a fluid particle remains constant.
Q. 4 An ideal fluid flows through a pipe of circular cross-section made of two sections with diameters 2.5 cm and 3.75 cm. The ratio of the velocities in the two pipes is
() 9:4
() 3:2
() 2:3
Please disable the adBlock and continue. Thank you.
