Fluids And Pressure Test

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Fluids And Pressure Test - 5

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Question 1
1 / -0

A boat of mass 650 kg floats on water. What volume of water does it displace?

A
0.42 m³

B
0.56 m³

C
0.65 m³

D
0.72 m³

Solution

V = 650 / 1000 = 0.65 m³
Question 2
1 / -0

Which of the following is based on Archimedes' principle?

A
Lactometer

B
Barometer

C
Anemometer

D
Speedometer

Solution

Lactometer is based on Archimedes' principle.
Question 3
1 / -0

A body floats in a liquid contained in a beaker. The whole system, as shown in the figure, falls freely under gravity. The upthrust on the body due to the liquid is

A
zero

B
equal to the weight of the liquid displaced

C
equal to the weight of the body

D
equal to the weight of the immersed portion of the body

Solution

The upthrust on the body due to the liquid is zero because the body is falling freely.
Question 4
1 / -0

The reading of a spring balance when a block is suspended from it in air is 60 N. This reading is changed to 40 N when the block is submerged in water. The specific gravity of the block must be

A
3

B
2

C
6

D
3/2

Solution

Specific gravity = Weight in air/Loss of weight in water = 60/(60 - 40) = 3
Question 5
1 / -0

A solid cylinder floats in water, with 4/5 of its volume inside water. The density of the material of the cylinder is

A
80 kg/m³

B
800 kg/m³

C
600 kg/m³

D
500 kg/m³

Solution

Density of water, d_w = 1000 kg/m³^{As the solid cylinder floats in water, according to the Archimedes's principle,}^{Weight of cylinder = Weight of water replaced by the cylinder}^Hence,
Question 6
1 / -0

The upthrust on a body immersed in a fluid is equal to the

A
mass of liquid displaced

B
weight of fluid displaced

C
volume of fluid displaced

D
density of fluid displaced

Solution

The upthrust on a body immersed in a fluid is equal to the weight of fluid displaced
Question 7
1 / -0

The buoyant force acting on a fully submerged body depends on

A
the mass of the body

B
the volume of the body

C
the depth of the point below the surface of water

D
None of the above

Solution

The buoyant force acting on a fully submerged body depends on the volume of the body.
Question 8
1 / -0

When a ship floats on water,

A
it does not displace water

B
the mass of water displaced is equal to the mass of the ship

C
the mass of water displaced is less than the mass of the ship

D
the mass of water displaced is greater than the mass of the ship

Solution

When a ship floats on water, the mass of water displaced is equal to the mass of the ship.
Question 9
1 / -0

When a piece of ice floating in a beaker of water completely melts, the level of water in the beaker

A
rises

B
falls

C
remains unchanged

D
rises or falls depending upon the quantity of ice and water

Solution

When a piece of ice floating in a beaker of water completely melts, the level of water in the beaker remains unchanged because the volume of ice decrease when change to water hence the level remains the same.
Question 10
1 / -0

Water falling vertically from the mouth of a tap in a streamline flow forms a tapering column as shown in the figure. Which of the following is the most correct explanation for this?

A
As the water falls down, its velocity increases resulting in decrease in pressure. So, it is then compressed by the surrounding air

B
The mass of water passing through any cross-section must remain constant. So in accordance with Av = constant (as liquid is incompressible), the area of cross-section decreases with increase in velocity.

C
Due to surface tension effect, exposed surface area of liquid decreases

D
To attain terminal velocity, area of cross –section decreases.

Solution

Water falling vertically from the mouth of a tap in a streamline flow forms a tapering column as shown in the figure. The mass of water passing through any cross-section must remain constant. So in accordance with Av = constant (as liquid is incompressible), the area of cross-section decreases with increase in velocity.
Question 11
1 / -0

Water is flowing through a pipe of uniform cross-section under constant pressure. At some place, the pipe becomes narrow. The pressure of water at that place

A
increases

B
decreases

C
remains unchanged

D
depends on several factors

Solution

Water is flowing through a pipe of uniform cross-section under constant pressure. At some place, the pipe becomes narrow. The pressure of water at that place decreases because the flow velocity of water increases.
Question 12
1 / -0

Pressure applied to an enclosed fluid is transmitted undiminished to every portion of the fluid and the walls of the containing vessel. This law was first formulated by

A
Bernoulli

B
Archimedes'

C
Boyle

D
Pascal

Solution

Pressure applied to an enclosed fluid is transmitted undiminished to every portion of the fluid and the walls of the containing vessel. This law was first formulated by Pascal.
Question 13
1 / -0

Raindrops of different radii are falling through air. The terminal velocity of a drop of radius r will be proportional to

A
r³

B
r²

C
r

D

Solution

Raindrops of different radii are falling through air. The terminal velocity of a drop of radius r will be proportional to r²
Question 14
1 / -0

Why does a camel have large feet?

A
To minimise pressure on ground and prevent sinking

B
To increase friction

C
To help it absorb heat from sand

D
To prevent it from toppling

Solution

A camel has large feet to minimise the pressure on ground and prevent sinking because P = F / A.
Question 15
1 / -0

The tube shown below is of uniform cross–section. Liquid flows through it at a constant speed in the direction shown by the arrows. The liquid exerts on the tube

A
a net force to the right

B
a net force to the left

C
a clockwise torque

D
an anti-clockwise torque

Solution
Question 16
1 / -0

Two stretched membranes of area 2 cm²and 3 cm² and are placed in a liquid at the same depth. The ratio of the pressures on them is

A
1 : 1

B
2 : 3

C
3 : 2

D
2² : 3²

Solution

Two stretched membranes of area 2 cm² and 3 cm² and are placed in a liquid at the same depth. The ratio of the pressures on them is 1 : 1 beacuse Pressure is independent of area of cross section
Question 17
1 / -0

What is the variation of pressure as depth of a compressible fluid increases?

A
Increment

B
Decrement

C
Constant

D
First decrement, then increment

Solution

Increment is the variation of pressure as depth of a compressible fluid increases.
Question 18
1 / -0

A tank, which is open at the top, contains a liquid up to a height H. A small hole is made in the side of the tank at a distance y below the liquid surface. The liquid emerging from the hole lands at a distance x from the tank. Which of the following is correct?

A
If y is increased from zero to H, x will first increase and then decrease.

B
x is maximum for y = H.

C
The maximum value of x is 2 H.

D
The maximum value of x will depend on the density of the liquid.

Solution

Velocity of the efflux is given by:

Time taken by liquid stream to strike the horizontal surface at x:

Hence,

Or,

Hence, first 'x' will increase and become maximum at and then it will start decreasing.
Question 19
1 / -0

Why does the surface of water in a tumbler remain horizontal?

A
Due to surface tension

B
Due to cohesive force

C
Due to gravitational force

D
Due to adhesive force

Solution

Due to cohesive force the surface of water in a tumbler remain horizontal
Question 20
1 / -0

A vertical glass capillary tube, open at both ends, contains some water. Which of the following shapes may be taken by the water in the tube?

A

B

C

D

Solution

The two liquid surfaces must provide a net upward force due to surface tension to balance the weight of liquid column.