31 + Mcqs in Buoyancy Page 1 McqOptions

1.	Submarines use principle of ‘neutral buoyancy’ to go into the water.
A.	True
B.	False
Answer» B. False

Discussion

2.	As a balloon rises in the air its volume increases, at the end it acquires a stable height and cannot rise any further.
A.	True
B.	False
Answer» B. False

Discussion

3.	Assertion: A needle placed carefully on the surface of the water may float, whereas a ball of the same material will always sink.Reason: The buoyancy of an object depends both on the material and shape of the object
A.	Both assertion and reason are true and the reason is the correct explanation of the assertion
B.	Both assertion and reason are true but the reason is not the correct explanation of the assertion
C.	Assertion is true but the reason is false
D.	Assertion and reason is false
Answer» D. Assertion and reason is false

Discussion

4.	The water droplets in free fall are spherical due to ___________
A.	Gravity
B.	Viscosity
C.	Surface tension
D.	Intermolecular attraction
Answer» D. Intermolecular attraction

Discussion

5.	A wooden block is taken to the bottom of a deep, calm lake of water and then released. It rises up with a ___________
A.	Constant acceleration
B.	Decreasing acceleration
C.	Constant velocity
D.	Decreasing velocity
Answer» B. Decreasing acceleration

Discussion

6.	Spherical balls of radius R are falling in a viscous fluid of viscosity Ƞ with a velocity v. The retarding viscous force acting on the spherical ball is ___________
A.	Directly proportional to R but inversely proportional to v
B.	Directly proportional to both radius R and velocity v
C.	Inversely proportional to both radius R and velocity v
D.	Inversely proportional to R but directly proportional to velocity v
Answer» C. Inversely proportional to both radius R and velocity v

Discussion

7.	A boat having a length of 3m and breadth 2m is floating on a lake. The boat sinks by one cm when a man gets on it. What is the mass of the man?
A.	6kg
B.	60kg
C.	16kg
D.	600kg
Answer» C. 16kg

Discussion

8.	A solid weight 6kg in air. If its density is 2000kgm-3, what will be its apparent weight in water?
A.	6kg
B.	2kg
C.	3kg
D.	5kg
Answer» D. 5kg

Discussion

9.	Assertion: A hydrogen filled balloon stops using after it has attained a certain height in the sky.Reason: The atmospheric pressure decreases with height and becomes zero when maximum height is attained.
A.	Both assertion and reason are true and the reason is the correct explanation of the assertion
B.	Both assertion and reason are true but the reason is not the correct explanation of the assertion
C.	Assertion is true but the reason is false
D.	Assertion and reason is false
Answer» D. Assertion and reason is false

Discussion

10.	When the temperature is increased, the angle of contact of a liquid?
A.	Increase
B.	Decrease
C.	Remains the same
D.	First increases and then decreases
Answer» B. Decrease

Discussion

11.	In incompressible fluid flows steadily through a cylindrical pipe which had a radius 2R at point A and R at a point B further along the flow direction. If the velocity at A is v, then that at B is?
A.	v/2
B.	v
C.	2v
D.	4v
Answer» E.

Discussion

12.	A_WOODEN_BLOCK_IS_TAKEN_TO_THE_BOTTOM_OF_A_DEEP,_CALM_LAKE_OF_WATER_AND_THEN_RELEASED._IT_RISES_UP_WITH_A?$
A.	Constant acceleration
B.	Decreasing acceleration
C.	Constant velocity
D.	Decreasing velocity
Answer» B. Decreasing acceleration

Discussion

13.	AS_A_BALLOON_RISES_IN_THE_AIR_ITS_VOLUME_INCREASES,_AT_THE_END_IT_ACQUIRES_A_STABLE_HEIGHT_AND_CANNOT_RISE_ANY_FURTHER.?$
A.	True
B.	False
Answer» B. False

Discussion

14.	Assertion: A needle placed carefully on the surface of the water may float, whereas a ball of the same material will always sink.$
A.
B.	Both assertion and reason are true and the reason is the correct explanation of the assertion
C.	Both assertion and reason are true but the reason is not the correct explanation of the assertion
Answer» D.

Discussion

15.	The_water_droplets_in_free_fall_are_spherical_due_to$
A.	Gravity
B.	Viscosity
C.	Surface tension
D.	Intermolecular attraction
Answer» D. Intermolecular attraction

Discussion

16.	Submarines_use_principle_of_‚Äö√Ñ√∂‚àö√ë‚àö‚â§neutral_buoyancy‚Äö√Ñ√∂‚àö√ë‚àö¬•_to_go_into_the_water.$#
A.	True
B.	False
Answer» B. False

Discussion

17.	Spherical balls of radius R are falling in a viscous fluid of viscosity ¬¨¬™‚Äö√Ñ‚Ä† with a velocity v. The retarding viscous force acting on the spherical ball i?#
A.	Directly proportional to R but inversely proportional to v
B.	Directly proportional to both radius R and velocity v
C.	Inversely proportional to both radius R and velocity v
D.	Inversely proportional to R but directly proportional to velocity v
Answer» C. Inversely proportional to both radius R and velocity v

Discussion

18.	What happens to the buoyant force acting on the airship as it rises in the air?
A.	Buoyant force increases
B.	Buoyant force decreases
C.	Buoyant force remains constant
D.	Buoyant force first increases then shows decrease
Answer» C. Buoyant force remains constant

Discussion

19.	It is difficult to cook food at the mountain.
A.	True
B.	False
Answer» B. False

Discussion

20.	How can relatively denser object be made to float on the less dense fluid?
A.	By altering the shape.
B.	By altering the forces acting on the object
C.	By altering the shear forces acting on the object
D.	None of the mentioned
Answer» B. By altering the forces acting on the object

Discussion

21.	A boat having a length of 3m and breadth 2m is floating on a lake. The boat sinks by one cm, when a man gets on it. What is the mass of the man?
A.	6kg
B.	60kg
C.	16kg
D.	600kg
Answer» C. 16kg

Discussion

22.	What is the principal cause of action of buoyant force on a body submerged partially or fully in fluid?
A.	Displacement of fluid due to submerged body
B.	Development of force due to dynamic action
C.	Internal shear forces mitigating external forces
D.	None of the mentioned
Answer» B. Development of force due to dynamic action

Discussion

23.	A solid weight 6kg in air. If its density is 2000kgm-3, what will be its apparent weight in water?
A.	6kg
B.	2kg
C.	3kg
D.	5kg
Answer» D. 5kg

Discussion

24.	Find the density of metallic body which floats at the interface of mercury of sp.gr 13.6 and water such that 40 % of its volume is sub-merged in mercury and 60% in water.
A.	6040 kg/m<sup>3</sup>
B.	12080 kg/m<sup>3</sup>
C.	24160 kg/m<sup>3</sup>
D.	3020 kg/m<sup>3</sup>
Answer» B. 12080 kg/m<sup>3</sup>

Discussion

25.	A cube of wood floating in water supports a 200g mass at the centre of its top face. When the mass is removed, the mass rises by 2cm. Determine the volume of cube.
A.	1000cm<sup>3</sup>
B.	100cm<sup>3</sup>
C.	10cm<sup>3</sup>
D.	1cm<sup>3</sup>
Answer» B. 100cm<sup>3</sup>

Discussion

26.	A body of dimensions 2.7 m * 3.8 m * 2.5 m, weighs 2500 N in water.Find its weight in air.
A.	254.12 kN
B.	508.25 kN
C.	101.65 kN
D.	127.06 kN
Answer» B. 508.25 kN

Discussion

27.	Assertion: A hydrogen filled balloon stops using after it has attained a certain height in the sky
A.
B.	Both assertion and reason are true and the reason is the correct explanation of the assertion
C.	Both assertion and reason are true but the reason is not the correct explanation of the assertion
Answer» D.

Discussion

28.	A stone weighs 650 N in air and 275 N in water. Compute its specific gravity.
A.	1.73
B.	2.45
C.	3.46
D.	0.865
Answer» B. 2.45

Discussion

29.	When the temperature is increased, the angle of contact of a liquid
A.	Increase
B.	Decrease
C.	Remains the same
D.	First increases and then decreases
Answer» B. Decrease

Discussion

30.	A stone weighs 450 N in air and 200 N in water. Compute the volume of stone.
A.	.025 m<sup>3</sup>
B.	.05 m<sup>3</sup>
C.	.075 m<sup>3</sup>
D.	None of the mentioned
Answer» B. .05 m<sup>3</sup>

Discussion

31.	Find the position of centre of buoyancy for a wooden block of width 3.5 m and depth 1 m, when it floats horizontally in water. The density of wooden block id 850 kg/m3 and its length 7.0 m.
A.	0.95
B.	0.85
C.	1.05
D.	1.65
Answer» C. 1.05

Discussion

Explore topic-wise MCQs in Fluid Mechanics.

Submarines use principle of ‘neutral buoyancy’ to go into the water.

As a balloon rises in the air its volume increases, at the end it acquires a stable height and cannot rise any further.

Assertion: A needle placed carefully on the surface of the water may float, whereas a ball of the same material will always sink.Reason: The buoyancy of an object depends both on the material and shape of the object

The water droplets in free fall are spherical due to ___________

A wooden block is taken to the bottom of a deep, calm lake of water and then released. It rises up with a ___________

Spherical balls of radius R are falling in a viscous fluid of viscosity Ƞ with a velocity v. The retarding viscous force acting on the spherical ball is ___________

A boat having a length of 3m and breadth 2m is floating on a lake. The boat sinks by one cm when a man gets on it. What is the mass of the man?

A solid weight 6kg in air. If its density is 2000kgm-3, what will be its apparent weight in water?

Assertion: A hydrogen filled balloon stops using after it has attained a certain height in the sky.Reason: The atmospheric pressure decreases with height and becomes zero when maximum height is attained.

When the temperature is increased, the angle of contact of a liquid?

In incompressible fluid flows steadily through a cylindrical pipe which had a radius 2R at point A and R at a point B further along the flow direction. If the velocity at A is v, then that at B is?

A_WOODEN_BLOCK_IS_TAKEN_TO_THE_BOTTOM_OF_A_DEEP,_CALM_LAKE_OF_WATER_AND_THEN_RELEASED._IT_RISES_UP_WITH_A?$

AS_A_BALLOON_RISES_IN_THE_AIR_ITS_VOLUME_INCREASES,_AT_THE_END_IT_ACQUIRES_A_STABLE_HEIGHT_AND_CANNOT_RISE_ANY_FURTHER.?$

Assertion: A needle placed carefully on the surface of the water may float, whereas a ball of the same material will always sink.$

The_water_droplets_in_free_fall_are_spherical_due_to$

Submarines_use_principle_of_‚Äö√Ñ√∂‚àö√ë‚àö‚â§neutral_buoyancy‚Äö√Ñ√∂‚àö√ë‚àö¬•_to_go_into_the_water.$#

Spherical balls of radius R are falling in a viscous fluid of viscosity ¬¨¬™‚Äö√Ñ‚Ä† with a velocity v. The retarding viscous force acting on the spherical ball i?#

What happens to the buoyant force acting on the airship as it rises in the air?

It is difficult to cook food at the mountain.

How can relatively denser object be made to float on the less dense fluid?

A boat having a length of 3m and breadth 2m is floating on a lake. The boat sinks by one cm, when a man gets on it. What is the mass of the man?

What is the principal cause of action of buoyant force on a body submerged partially or fully in fluid?

A solid weight 6kg in air. If its density is 2000kgm-3, what will be its apparent weight in water?

Find the density of metallic body which floats at the interface of mercury of sp.gr 13.6 and water such that 40 % of its volume is sub-merged in mercury and 60% in water.

A cube of wood floating in water supports a 200g mass at the centre of its top face. When the mass is removed, the mass rises by 2cm. Determine the volume of cube.

A body of dimensions 2.7 m * 3.8 m * 2.5 m, weighs 2500 N in water.Find its weight in air.

Assertion: A hydrogen filled balloon stops using after it has attained a certain height in the sky

A stone weighs 650 N in air and 275 N in water. Compute its specific gravity.

When the temperature is increased, the angle of contact of a liquid

A stone weighs 450 N in air and 200 N in water. Compute the volume of stone.

Find the position of centre of buoyancy for a wooden block of width 3.5 m and depth 1 m, when it floats horizontally in water. The density of wooden block id 850 kg/m3 and its length 7.0 m.