The radius of a soap bubble is increased from R to 2 R. Work done in this process (T = surface tension) is:
1. | 24 πR2T | 2. | 48 πR2T |
3. | 12 πR2T | 4. | 36 πR2T |
A cubical vessel of height 1 m is full of water. Find the work done in pumping out whole water.
1. 49 J
2. 490 J
3. 4900 J
4. 49000 J
The flow rate from a tap of diameter 1.25 cm is 3 lit/min. The coefficient of viscosity of water is Pas. The nature of flow is :
1. Turbulent
2. Laminar
3. Neither laminar nor turbulent
4. data inadequate
Water flowing from a hose pipe fills a 15-liter container in one minute. The speed of water from the free opening of radius 1 cm is (in ms) :
1. 2.5
2.
3.
4. 5
Work of 6.0 x 10 Joule is required to be done in increasing the size of a soap film from 10cm x 6cm to 10cm x 11cm. The surface tension of the film is :
1. 5 x 10 N/m
2. 6 x 10 N/m
3. 1.5 x 10 N/m
4. 1.2 x 10 N/m
When a cylindrical tube is dipped vertically into a liquid the angle of contact is 140o. When the tube is dipped with an inclination of 40o, the angle of contact is-
1.
2.
3.
4.
Two liquid drops have their diameters as 1 mm and 2 mm. The ratio of excess pressure in them is :
1. 1:2
2. 2:1
3. 4:1
4. 1:4
The rate of flowing of water from the orifice in a wall of a tank will be more if the orifice is:
1. Near the bottom
2. Near the upper end
3. Exactly in the middle
4. Does not depend upon the position of the orifice
Water flows through a frictionless duct with a cross-section varying as shown in the figure. Pressure p at points along the axis is represented by
1. 2.
3. 4.
In the figure below is shown the flow of liquid through a horizontal pipe. Three tubes A, B, and C are connected to the pipe. The radius of the pipe at A, B, and C is respectively 2 cm, 1 cm, and 2 cm. It can be said that the :
1. Height of the liquid in the tube A is maximum
2. Height of the liquid in the tubes A and B is the same
3. Height of the liquid in all the three tubes is the same
4. Height of the liquid in the tubes A and C is the same
Two spherical soap bubbles of radii r1 and r2 in vaccum collapse under isothermal condition. The resulting bubble has radius equal to :
1.
2.
3.
4.
An incompressible liquid travels as shown in the figure. The speed of the fluid in the lower branch will :
1. 1 m/s
2. 1.5 m/s
3. 2.25 m/s
4. 3 m/s
A U tube with both ends open to the atmosphere,is partially filled with water. Oil, which is immiscible with water, is poured into one side until it stands at a distance of 10mm above the water level on the other side. Meanwhile the water rises by 65 mm from its original level (see diagram). The density of the oil is
(a)
(b)
(c)
(d)
A rectangular film of liquid is extended from (4 cm ) to \((4 ~\text{cm}\times 5 ~\text{cm})\). If the work done is J, the value of the surface tension of the liquid is:
1. | 0.250 Nm-1 | 2. | 0.125 Nm-1 |
3. | 0.2 Nm-1 | 4. | 8.0 Nm-1 |
Water rises to a height h in capillary tube . If the length of capillary tube above the surface of water is made less than h, then
(1) water rises upto the tip of capillary tube and then starts overflowing like a fountain
(2) water rises upto the top of capillary tube and stays there without overflowing
(3) water rises upto a point a little below the top and stays there
(4) water does not rise at all
If pressure at half the depth of a lake is equal to 2/3 pressure at the bottom of the lake ,then what is the depth of the lake ?
(a) 10 m (b) 20 m
(c) 60 m (d) 30 m
Two bodies are in equilibrium when suspended in water from the arms of a balance. The mass of one body is \(36\) g and its density is \(9\) g/cm3. If the mass of the other is \(48\) g, its density in g/cm3 will be:
1.
2.
3. \(3\)
4. \(5\)
An inverted bell lying at the bottom of a lake 47.6 m deep has 50 cm3 of air trapped in it. The bell is brought to the surface of the lake. The volume of the trapped air will be (atmospheric pressure = 70 cm of Hg and density of Hg = 13.6 g/cm3)
(1) 350 cm3
(2) 300 cm3
(3) 250 cm3
(4) 22 cm3
A siphon in use is demonstrated in the following figure. The density of the liquid flowing in siphon is 1.5 gm/cc. The pressure difference between the point P and S will be
(1)
(2)
(3) Zero
(4) Infinity
The height of a mercury barometer is 75 cm at sea level and 50 cm at the top of a hill. Ratio of density of mercury to that of air is . The height of the hill is
(1) 250 m
(2) 2.5 km
(3) 1.25 km
(4) 750 m
Equal masses of water and a liquid of relative density 2 are mixed together, then the mixture has a density of
(1) 2/3
(2) 4/3
(3) 3/2
(4) 3
The value of g at a place decreases by 2%. The barometric height of mercury
(1) Increases by 2%
(2) Decreases by 2%
(3) Remains unchanged
(4) Sometimes increases and sometimes decreases
A barometer kept in a stationary elevator reads 76 cm. If the elevator starts accelerating up, the reading will be
(1) Zero
(2) Equal to 76 cm
(3) More than 76 cm
(4) Less than 76 cm
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 beaker will
1. Increase
2. Decrease
3. Remain constant
4. First decrease and then increase
A vertical U-tube of uniform inner cross section, contains mercury in both its arms. A glycerin (density = 1.3 g/) column of length 10 cm is introduced into one of its arms. Oil of density 0.8 gm/ is poured into the other arm until the upper surfaces of the oil and glycerin are at the same horizontal level. Find the length of the oil column. [Density of mercury = 13.6 g/]
1. 10.4 cm
2. 8.2 cm
3. 7.2 cm
4. 9.6 cm
If two liquids of same volume but different densities and are mixed, then density of mixture is given by
(1)
(2)
(3)
(4)
For the figures given below, the correct observation is:
1. | pressure at the bottom of the tank (a) is greater than at the bottom of the tank (b). |
2. | pressure at the bottom of the tank (a) is lesser than at the bottom of (b). |
3. | pressure depends upon the shape of the container. |
4. | pressure at the bottom of (a) and (b) are the same. |
A metallic block of density 5 gm and having dimensions 5 cm × 5 cm × 5 cm is weighed in water. Its apparent weight will be
(2) 5 × 5 × 5 × 5 gf
(3) 4 × 4 × 4 × 4 gf
(4) 5 × 4 × 4 × 4 gf
(d) 4 × 5 × 5 × 5 gf
A hollow sphere of volume V is floating on water surface with half immersed in it. What should be the minimum volume of water poured inside the sphere so that the sphere now sinks into the water ?
(1) V/2
(2) V/3
(3) V/4
(4) V
A boat carrying steel balls is floating on the surface of water in a tank. If the balls are thrown into the tank one by one, how will it affect the level of water?
1. | It will remain unchanged |
2. | It will rise |
3. | It will fall |
4. | First it will first rise and then fall |
Construction of submarines is based on
(1) Archimedes’ principle
(2) Bernoulli’s theorem
(3) Pascal’s law
(4) Newton’s laws
The velocity of kerosene oil in a horizontal pipe is 5 m/s. If , then the velocity head of oil will be:
1. 1.25 m
2. 12.5 m
3. 0.125 m
4. 125 m
Water rises against gravity in a capillary tube when its one end is dipped into water because
(1) Pressure below the meniscus is less than atmospheric pressure
(2) Pressure below the meniscus is more than atmospheric pressure
(3) Capillary attracts water
(4) Of viscosity
There is a horizontal film of soap solution. On it, a thread is placed in the form of a loop. The film is pierced inside the loop and the thread becomes a circular loop of radius R. If the surface tension of the loop is T, then what will be the tension in the thread?
1.
2.
3.
4.
Which graph represents the variation of surface tension with temperature over small temperature ranges for water?
1.
2.
3.
4.
The wettability of a surface by a liquid depends primarily on
(1) viscosity
(2) surface tension
(3) density
(4) angle of contact between the surface and the liquid
A certain number of spherical drops of a liquid of radius 'r' coalesce to form a single drop of radius 'R' and volume 'V'. If 'T' is the surface tension of the liquid then
(1)
(2)
(3)
(4) Energy is neither released nor absorbed
The approximate depth of an ocean is 2700 m. The compressibility of water is 45.4 and density of water is . What fractional compression of water will be obtained at the bottom of the ocean?
(1)
(2)
(3)
(4)
A wind with speed 40 m blows parallel to the roof of a house. The area of the roof is 250 . Assuming that the pressure inside the house is atmospheric pressure, the force exerted by the wind on the roof and the direction of the force will be
(1) 4.8 N, upwards
(2) 2.4N, upwards
(3) 2.4, downwards
(4) 4.8N, downwards
The heart of a man pumps 5 L of blood through the arteries per minute at a pressure of 150 mm of mercury. If the density of mercury be , then the power of heart in Watt is
(1) 1.50
(2) 1.70
(3) 2.35
(4) 3.0
The cylindrical tube of a spray pump has radius R, one end of which has n fine holes, each of radius r. If the speed of the liquid in the tube is v, the speed of the ejection of the liquid through the holes is
(1)
(2)
(3)
(4)
Two non-mixing liquids of densities are put in a container. The height of each liquid is h. A solid cylinder of length L and density d is put in this container. The cylinder floats with its axis vertical and length pL(p<1) in the denser liquid. The density d is equal to
(1) [2 + (n -1)p]
(2) [1 + (n - 1)p]
(3) [1 + (n + 1)p]
(4) [2 + (n + 1)p]
Three liquids of densities , having the same value of surface tension T, rise to the same height in three identical capillaries. The angles of contact obey
(1)
(2)
(3)
(4)
A U-tube, with both ends open to the atmosphere, is partially filled with water. Oil, which is immiscible with water, is poured into one side until it stands at a distance of 10 mm above the water level on the other side. Meanwhile, the water rises by 65 mm from its original level (see diagram). The density of the oil is
(1) 425 kg
(2) 800 kg
(3) 928 kg
(4) 650 kg
A small sphere of radius 'r' falls from rest in a viscous liquid. As a result, heat is produced due to the viscous force. The rate of production of heat when the sphere attains its terminal velocity is proportional to
(1)
(2)
(3)
(4)