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Selina solutions for Class 9 Physics chapter 5 - Upthrust in Fluids, Archimedes’ Principle and Floatation

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Selina Selina ICSE Concise Physics Class 9

Selina ICSE Concise Physics for Class 9 - Shaalaa.com

Chapter 5: Upthrust in Fluids, Archimedes’ Principle and Floatation

Exercise - 5(A)Exercise - 5(B)Exercise - 5(C)

Selina solutions for Class 9 Physics Chapter 5 Exercise Exercise - 5(A) [Pages 109 - 110]

Exercise - 5(A) | Q 1 | Page 109

What do you understand by the term upthrust of a fluid? Describe an experiment to show its existence. 

Exercise - 5(A) | Q 1 | Page 109

What do you understand by the term upthrust of a fluid? Describe an experiment to show its existence. 

Exercise - 5(A) | Q 2 | Page 109

In what direction and at what point does the buoyant force on a body due to a liquid act? 

Exercise - 5(A) | Q 2 | Page 109

In what direction and at what point does the buoyant force on a body due to a liquid act? 

Exercise - 5(A) | Q 3 | Page 109

What is meant by the term buoyancy? 

Exercise - 5(A) | Q 3 | Page 109

What is meant by the term buoyancy? 

Exercise - 5(A) | Q 4 | Page 109

Define upthrust and state its S.I. unit. 

Exercise - 5(A) | Q 4 | Page 109

Define upthrust and state its S.I. unit. 

Exercise - 5(A) | Q 5 | Page 109

What is the cause of upthrust? At which point can it be considered to act? 

Exercise - 5(A) | Q 5 | Page 109

What is the cause of upthrust? At which point can it be considered to act? 

Exercise - 5(A) | Q 6 | Page 109

Why is a force needed to keep a block of wood inside water? 

Exercise - 5(A) | Q 6 | Page 109

Why is a force needed to keep a block of wood inside water? 

Exercise - 5(A) | Q 7 | Page 109

A piece of wood if left under water comes to the surface. Explain the reason. 

Exercise - 5(A) | Q 7 | Page 109

A piece of wood if left under water comes to the surface. Explain the reason. 

Exercise - 5(A) | Q 8 | Page 109

Describe an experiment to show that a body immersed in a liquid appears lighter than it really is. 

Exercise - 5(A) | Q 8 | Page 109

Describe an experiment to show that a body immersed in a liquid appears lighter than it really is. 

Exercise - 5(A) | Q 9 | Page 109

Will a body weigh more in air or vacuum when weighed with a spring balance? Give a reason for your answer. 

Exercise - 5(A) | Q 9 | Page 109

Will a body weigh more in air or vacuum when weighed with a spring balance? Give a reason for your answer. 

Exercise - 5(A) | Q 10 | Page 110

A metal solid cylinder tied to a thread is hanging from the hook of a spring balance. The cylinder is gradually immersed into the water contained in a jar. What changes do you expect in the readings of the spring balance? Explain your answer. 

Exercise - 5(A) | Q 10 | Page 110

A metal solid cylinder tied to a thread is hanging from the hook of a spring balance. The cylinder is gradually immersed into the water contained in a jar. What changes do you expect in the readings of the spring balance? Explain your answer. 

Exercise - 5(A) | Q 11 | Page 110

A body dipped into a liquid experiences an upthrust. State two factors on which upthrust on the body depends. 

Exercise - 5(A) | Q 11 | Page 110

A body dipped into a liquid experiences an upthrust. State two factors on which upthrust on the body depends. 

Exercise - 5(A) | Q 12 | Page 110

How is the upthrust related to the volume of the body submerged in a liquid? 

Exercise - 5(A) | Q 12 | Page 110

How is the upthrust related to the volume of the body submerged in a liquid? 

Exercise - 5(A) | Q 13 | Page 110

A bunch of feathers and a stone of the same mass are released simultaneously in air. Which will fall faster and why? How will your observation be different if they are released simultaneously in vacuum?

Exercise - 5(A) | Q 13 | Page 110

A bunch of feathers and a stone of the same mass are released simultaneously in air. Which will fall faster and why? How will your observation be different if they are released simultaneously in vacuum?

Exercise - 5(A) | Q 14 | Page 110

A body experiences an upthrust F1 in river water and F2 in sea water when dipped up to the same level. Which is more, F1 or F2? Give reason. 

Exercise - 5(A) | Q 14 | Page 110

A body experiences an upthrust F1 in river water and F2 in sea water when dipped up to the same level. Which is more, F1 or F2? Give reason. 

Exercise - 5(A) | Q 15 | Page 110

A small block of wood is completely immersed in (i) water, (ii) glycerine and then released. In each case, What do you observe? Explain the difference in your observation in the two cases. 

Exercise - 5(A) | Q 15 | Page 110

A small block of wood is completely immersed in (i) water, (ii) glycerine and then released. In each case, What do you observe? Explain the difference in your observation in the two cases. 

Exercise - 5(A) | Q 16 | Page 110

A body of volume V and density ρ is kept completely immersed in a liquid of density ρL. If g is the acceleration due to gravity, then write expressions for the following:

(i) The weight of the body, (ii) The upthrust on the body,

(iii) The apparent weight of the body in liquid, (iv) The loss in weight of the body. 

Exercise - 5(A) | Q 16 | Page 110

A body of volume V and density ρ is kept completely immersed in a liquid of density ρL. If g is the acceleration due to gravity, then write expressions for the following:

(i) The weight of the body, (ii) The upthrust on the body,

(iii) The apparent weight of the body in liquid, (iv) The loss in weight of the body. 

Exercise - 5(A) | Q 17 | Page 110

A body held completely immersed inside a liquid experiences two forces:

(i) F1, the force due to gravity and

(ii) F2, the buoyant force.

Draw a diagram showing the direction of these forces acting on the body and state the condition when the body will float or sink. 

Exercise - 5(A) | Q 17 | Page 110

A body held completely immersed inside a liquid experiences two forces:

(i) F1, the force due to gravity and

(ii) F2, the buoyant force.

Draw a diagram showing the direction of these forces acting on the body and state the condition when the body will float or sink. 

Exercise - 5(A) | Q 18.1 | Page 110

Complete the following sentence :

Two balls, one of iron and the other of aluminium experience the same upthrust when dipped completely in water if _____________ .

Exercise - 5(A) | Q 18.1 | Page 110

Complete the following sentence :

Two balls, one of iron and the other of aluminium experience the same upthrust when dipped completely in water if _____________ .

Exercise - 5(A) | Q 18.2 | Page 110

Complete the following sentence :

An empty tin container with its mouth closed has an average density equal to that of a liquid. The container is taken 2 m below the surface of that liquid and is left there. Then the container will ____________ .

Exercise - 5(A) | Q 18.2 | Page 110

Complete the following sentence :

An empty tin container with its mouth closed has an average density equal to that of a liquid. The container is taken 2 m below the surface of that liquid and is left there. Then the container will ____________ .

Exercise - 5(A) | Q 18.3 | Page 110

Complete the following sentence :

A piece of wood is held under water. The upthrust on it will be ___________  the weight of the wood piece. 

Exercise - 5(A) | Q 18.3 | Page 110

Complete the following sentence :

A piece of wood is held under water. The upthrust on it will be ___________  the weight of the wood piece. 

Exercise - 5(A) | Q 19 | Page 110

Prove that the loss in weight of a body when immersed wholly or partially in a liquid is equal to the buoyant force (or upthrust) and this loss is because of the difference in pressure exerted by liquid on the upper and lower surfaces of the submerged part of body. 

Exercise - 5(A) | Q 19 | Page 110

Prove that the loss in weight of a body when immersed wholly or partially in a liquid is equal to the buoyant force (or upthrust) and this loss is because of the difference in pressure exerted by liquid on the upper and lower surfaces of the submerged part of body. 

Exercise - 5(A) | Q 20 | Page 110

A sphere of iron and another sphere of wood of the same radius are held under water. Compare the upthrust on the two spheres.

[Hint: Both have equal volume inside the water].

Exercise - 5(A) | Q 20 | Page 110

A sphere of iron and another sphere of wood of the same radius are held under water. Compare the upthrust on the two spheres.

[Hint: Both have equal volume inside the water].

Exercise - 5(A) | Q 21 | Page 110

A sphere of iron and another of wood, both of same radius are placed on the surface of water. State which of the two will sink? Give a reason for your answer. 

Exercise - 5(A) | Q 21 | Page 110

A sphere of iron and another of wood, both of same radius are placed on the surface of water. State which of the two will sink? Give a reason for your answer. 

Exercise - 5(A) | Q 22 | Page 110

How does the density of material of a body determine whether it will float or sink in water? 

Exercise - 5(A) | Q 22 | Page 110

How does the density of material of a body determine whether it will float or sink in water? 

Exercise - 5(A) | Q 23 | Page 110

A body of density ρ is immersed in a liquid of density ρL. State the condition when the body will (i) float and (ii) sink in the liquid. 

Exercise - 5(A) | Q 23 | Page 110

A body of density ρ is immersed in a liquid of density ρL. State the condition when the body will (i) float and (ii) sink in the liquid. 

Exercise - 5(A) | Q 24 | Page 110

It is easier to lift a heavy stone under water than in air. Explain. 

Exercise - 5(A) | Q 24 | Page 110

It is easier to lift a heavy stone under water than in air. Explain. 

Exercise - 5(A) | Q 25 | Page 110

State the Archimedes' principle. 

Exercise - 5(A) | Q 25 | Page 110

State the Archimedes' principle. 

Exercise - 5(A) | Q 26 | Page 110

Describe an experiment to verify the Archimedes' principle. 

Exercise - 5(A) | Q 26 | Page 110

Describe an experiment to verify the Archimedes' principle. 

Selina solutions for Class 9 Physics Chapter 5 Exercise Exercise - 5(A) [Page 110]

Exercise - 5(A) | Q 1 | Page 110

A body will experience minimum upthrust when it is completely immersed in : 

  • Turpentine  

  • Water

  • Glycerine   

  • Mercury 

Exercise - 5(A) | Q 1 | Page 110

A body will experience minimum upthrust when it is completely immersed in : 

  • Turpentine  

  • Water

  • Glycerine   

  • Mercury 

Exercise - 5(A) | Q 2 | Page 110

The S.I. unit of upthrust is : 

  • Pa

  • N

  • kg

  •  kg m2 

Exercise - 5(A) | Q 2 | Page 110

The S.I. unit of upthrust is : 

  • Pa

  • N

  • kg

  •  kg m2 

Exercise - 5(A) | Q 3 | Page 110

A body of density ρ sinks in a liquid of density ρL.  The densities ρ and ρL are related as :

  • ρ = ρL

  • ρ < ρL

  • ρ > ρL

  • Nothing can be said.

Exercise - 5(A) | Q 3 | Page 110

A body of density ρ sinks in a liquid of density ρL.  The densities ρ and ρL are related as :

  • ρ = ρL

  • ρ < ρL

  • ρ > ρL

  • Nothing can be said.

Selina solutions for Class 9 Physics Chapter 5 Exercise Exercise - 5(A) [Pages 110 - 111]

Exercise - 5(A) | Q 1 | Page 110

A body of volume 100 cm3 weighs 5 kgf in air. It is completely immersed in a liquid of density 1.8 x 103 kg m-3. Find:

(i) The upthrust due to liquid and

(ii) The weight of the body in liquid. 

Exercise - 5(A) | Q 1 | Page 110

A body of volume 100 cm3 weighs 5 kgf in air. It is completely immersed in a liquid of density 1.8 x 103 kg m-3. Find:

(i) The upthrust due to liquid and

(ii) The weight of the body in liquid. 

Exercise - 5(A) | Q 2 | Page 110

A body weighs 450 gf in air and 310 gf when completely immersed in water. Find 

(i) The volume of the body,

(ii) The loss in weight of the body, and

(iii) The upthrust on the body.

State the assumption made in part (i). 

Exercise - 5(A) | Q 2 | Page 110

A body weighs 450 gf in air and 310 gf when completely immersed in water. Find 

(i) The volume of the body,

(ii) The loss in weight of the body, and

(iii) The upthrust on the body.

State the assumption made in part (i). 

Exercise - 5(A) | Q 3 | Page 111

You are provided with a hollow iron ball A of volume 15 cm3 and mass 12 g and a solid iron ball B of mass 12 g. Both are placed on the surface of water contained in a large tub.

(a) Find upthrust on each ball.

(b) Which ball will sink? Give a reason for your answer. (Density of iron = 8.0 g cm-3) 

Exercise - 5(A) | Q 3 | Page 111

You are provided with a hollow iron ball A of volume 15 cm3 and mass 12 g and a solid iron ball B of mass 12 g. Both are placed on the surface of water contained in a large tub.

(a) Find upthrust on each ball.

(b) Which ball will sink? Give a reason for your answer. (Density of iron = 8.0 g cm-3) 

Exercise - 5(A) | Q 4 | Page 111

A solid of density 5000 kg m-3 weighs 0.5 kgf in air. It is completely immersed in water of density 1000 kg m-3. Calculate the apparent weight of the solid in water. 

Exercise - 5(A) | Q 4 | Page 111

A solid of density 5000 kg m-3 weighs 0.5 kgf in air. It is completely immersed in water of density 1000 kg m-3. Calculate the apparent weight of the solid in water. 

Exercise - 5(A) | Q 5 | Page 111

Two spheres A and B, each of volume 100 cm3 are placed on water (density = 1.0 g cm-3). The sphere A is made of wood of density 0.3 g cm-3 and the sphere B is made of iron of density 8.9 g cm-3.

(a) Find:

(i) The weight of each sphere, and

(ii) The upthrust on each sphere.

(b) Which sphere will float? Give reason. 

Exercise - 5(A) | Q 5 | Page 111

Two spheres A and B, each of volume 100 cm3 are placed on water (density = 1.0 g cm-3). The sphere A is made of wood of density 0.3 g cm-3 and the sphere B is made of iron of density 8.9 g cm-3.

(a) Find:

(i) The weight of each sphere, and

(ii) The upthrust on each sphere.

(b) Which sphere will float? Give reason. 

Exercise - 5(A) | Q 6 | Page 111

The mass of a block made of certain material is 13.5 kg and its volume is 15 × 10-3 m3.

(a) Calculate upthrust on the block if it is held fully immersed in water.

(b) Will the block float or sink in water when released? Give a reason for your answer.

(c) What will be the upthrust on block while floating?

Take density of water = 1000 kg m-3. 

Exercise - 5(A) | Q 6 | Page 111

The mass of a block made of certain material is 13.5 kg and its volume is 15 × 10-3 m3.

(a) Calculate upthrust on the block if it is held fully immersed in water.

(b) Will the block float or sink in water when released? Give a reason for your answer.

(c) What will be the upthrust on block while floating?

Take density of water = 1000 kg m-3. 

Exercise - 5(A) | Q 7 | Page 111

A piece of brass weighs 175 gf in air and 150 gf when fully submerged in water. The density of water is 1.0 g cm-3.

(i) What is the volume of the brass piece? (ii) Why does the brass piece weigh less in water? 

Exercise - 5(A) | Q 7 | Page 111

A piece of brass weighs 175 gf in air and 150 gf when fully submerged in water. The density of water is 1.0 g cm-3.

(i) What is the volume of the brass piece? (ii) Why does the brass piece weigh less in water? 

Exercise - 5(A) | Q 8 | Page 111

A metal cube of edge 5 cm and density 9 g cm-3 is suspended by a thread so as to be completely immersed in a liquid of density 1.2 g cm-3. Find the tension in thread. (Take g = 10 m s-2) 

Exercise - 5(A) | Q 8 | Page 111

A metal cube of edge 5 cm and density 9 g cm-3 is suspended by a thread so as to be completely immersed in a liquid of density 1.2 g cm-3. Find the tension in thread. (Take g = 10 m s-2) 

Exercise - 5(A) | Q 9 | Page 111

A block of wood is floating on water with its dimensions 50 cm x 50 cm x 50 cm inside water. Calculate the buoyant force acting on the block. Take g = 9.8 N kg-1. 

Exercise - 5(A) | Q 9 | Page 111

A block of wood is floating on water with its dimensions 50 cm x 50 cm x 50 cm inside water. Calculate the buoyant force acting on the block. Take g = 9.8 N kg-1. 

Exercise - 5(A) | Q 10 | Page 111

A body of mass 3.5 kg displaces 1000 cm3 of water when fully immersed inside it. Calculate: (i) the volume of body, (ii) the upthrust on body and (iii) the apparent weight of body in water. 

Exercise - 5(A) | Q 10 | Page 111

A body of mass 3.5 kg displaces 1000 cm3 of water when fully immersed inside it. Calculate: (i) the volume of body, (ii) the upthrust on body and (iii) the apparent weight of body in water. 

Selina solutions for Class 9 Physics Chapter 5 Exercise Exercise - 5(B), Exercise - 5(C) [Page 116]

Exercise - 5(B) | Q 1 | Page 116

Define the term density. 

Exercise - 5(B) | Q 1 | Page 116

Define the term density. 

Exercise - 5(B) | Q 2 | Page 116

What are the units density in (i) C.G.S. and (ii) S.I. system .

Exercise - 5(B) | Q 2 | Page 116

What are the units density in (i) C.G.S. and (ii) S.I. system .

Exercise - 5(B) | Q 3 | Page 116

Express the relationship between the C.G.S. and S.I. units of density. 

Exercise - 5(B) | Q 3 | Page 116

Express the relationship between the C.G.S. and S.I. units of density. 

Exercise - 5(B) | Q 4 | Page 116

'The density of iron is 7800 kg m-3'. What do you understand by this statement?

Exercise - 5(B) | Q 4 | Page 116

'The density of iron is 7800 kg m-3'. What do you understand by this statement?

Exercise - 5(B) | Q 5 | Page 116

Write the density of water at 4°C in S.I. unit .

Exercise - 5(B) | Q 5 | Page 116

Write the density of water at 4°C in S.I. unit .

Exercise - 5(B) | Q 6 | Page 116

How are the (i) Mass, (ii) Volume and (iii) Density of a metallic piece affected, if at all, with an increase in temperature?

Exercise - 5(B) | Q 6 | Page 116

How are the (i) Mass, (ii) Volume and (iii) Density of a metallic piece affected, if at all, with an increase in temperature?

Exercise - 5(B) | Q 7 | Page 116

Water is heated from 0°C to 10°C . How does the density of water change with temperature?

Exercise - 5(B) | Q 7 | Page 116

Water is heated from 0°C to 10°C . How does the density of water change with temperature?

Exercise - 5(B) | Q 8.1 | Page 116

Complete the following sentence.

Mass = .................... × density

Exercise - 5(B) | Q 8.1 | Page 116

Complete the following sentence.

Mass = .................... × density

Exercise - 5(B) | Q 8.2 | Page 116

Complete the following sentence.

S.I. unit of density is .......... .

Exercise - 5(B) | Q 8.2 | Page 116

Complete the following sentence.

S.I. unit of density is .......... .

Exercise - 5(B) | Q 8.3 | Page 116

Complete the following sentence.

Density of water is .... ... kg m-3.

Exercise - 5(B) | Q 8.3 | Page 116

Complete the following sentence.

Density of water is .... ... kg m-3.

Exercise - 5(B) | Q 8.4 | Page 116

Complete the following sentence.

Density in kg m-3 =  ............ × density in g cm-3

Exercise - 5(B) | Q 8.4 | Page 116

Complete the following sentence.

Density in kg m-3 =  ............ × density in g cm-3

Exercise - 5(B) | Q 9 | Page 116

What do you understand by the term relative density of a substance?

Exercise - 5(B) | Q 9 | Page 116

What do you understand by the term relative density of a substance?

Exercise - 5(B) | Q 10 | Page 116

What is the unit of relative density?

Exercise - 5(B) | Q 10 | Page 116

What is the unit of relative density?

Exercise - 5(C) | Q 11 | Page 116

Differentiate between density and relative density of a substance. 

Exercise - 5(C) | Q 11 | Page 116

Differentiate between density and relative density of a substance. 

Exercise - 5(B) | Q 12 | Page 116

With the use of Archimedes' principle, state how you will find relative density of a solid denser than water and insoluble in it. How will you modify your experiments if the solid is soluble in water? 

Exercise - 5(B) | Q 12 | Page 116

With the use of Archimedes' principle, state how you will find relative density of a solid denser than water and insoluble in it. How will you modify your experiments if the solid is soluble in water? 

Exercise - 5(B) | Q 13 | Page 116

A body weighs W gf in air and W1 gf when it is completely immersed in water. Find: (i) Volume of the body, (ii) Upthrust on the body and (iii) Relative density of the material of the body. 

Exercise - 5(B) | Q 13 | Page 116

A body weighs W gf in air and W1 gf when it is completely immersed in water. Find: (i) Volume of the body, (ii) Upthrust on the body and (iii) Relative density of the material of the body. 

Exercise - 5(B) | Q 14 | Page 116

Describe an experiment, using Archimedes principle, to find relative density of a liquid. 

Exercise - 5(B) | Q 14 | Page 116

Describe an experiment, using Archimedes principle, to find relative density of a liquid. 

Exercise - 5(B) | Q 15 | Page 116

A body weighs W1gf in air and when immersed in a liquid it weighs W2gf, while it weights W3gf on immersing it in water. Find: (i) volume of the body (ii) upthrust due to liquid (iii) relative density of the solid and (iv) relative density of the liquid.

Exercise - 5(B) | Q 15 | Page 116

A body weighs W1gf in air and when immersed in a liquid it weighs W2gf, while it weights W3gf on immersing it in water. Find: (i) volume of the body (ii) upthrust due to liquid (iii) relative density of the solid and (iv) relative density of the liquid.

Selina solutions for Class 9 Physics Chapter 5 Exercise Exercise - 5(B) [Page 116]

Exercise - 5(B) | Q 1 | Page 116

Relative density of a substance is expressed by comparing the density of that substance with the density of : 

  • Air

  • Mercury 

  • Water

  • Iron

Exercise - 5(B) | Q 1 | Page 116

Relative density of a substance is expressed by comparing the density of that substance with the density of : 

  • Air

  • Mercury 

  • Water

  • Iron

Exercise - 5(B) | Q 2 | Page 116

The unit of relative density is : 

  • g cm-3 

  • kg m-3 

  • m3 kg-1

  • no unit

Exercise - 5(B) | Q 2 | Page 116

The unit of relative density is : 

  • g cm-3 

  • kg m-3 

  • m3 kg-1

  • no unit

Exercise - 5(B) | Q 3 | Page 116

The density of water is : 

  • 1000 g cm-3

  • 1 kg m-3

  • 1 g cm-3

  • None of these.

Exercise - 5(B) | Q 3 | Page 116

The density of water is : 

  • 1000 g cm-3

  • 1 kg m-3

  • 1 g cm-3

  • None of these.

Selina solutions for Class 9 Physics Chapter 5 Exercise Exercise - 5(B) [Pages 116 - 117]

Exercise - 5(B) | Q 1 | Page 116

The density of copper is 8.83 g cm-3. Express it in kg m-3. 

Exercise - 5(B) | Q 1 | Page 116

The density of copper is 8.83 g cm-3. Express it in kg m-3. 

Exercise - 5(B) | Q 2 | Page 117

The relative density of mercury is 13.6. State its density in (i) C.G.S. unit and (ii) S.I. unit. 

Exercise - 5(B) | Q 2 | Page 117

The relative density of mercury is 13.6. State its density in (i) C.G.S. unit and (ii) S.I. unit. 

Exercise - 5(B) | Q 3 | Page 117

The density of iron is 7.8 x 103 kg m-3. What is its relative density? 

Exercise - 5(B) | Q 3 | Page 117

The density of iron is 7.8 x 103 kg m-3. What is its relative density? 

Exercise - 5(B) | Q 4 | Page 116

The relative density of silver is 10.8. Find its density. 

Exercise - 5(B) | Q 4 | Page 116

The relative density of silver is 10.8. Find its density. 

Exercise - 5(B) | Q 5 | Page 117

Calculate the mass of a body whose volume is 2 m3 and relative density is 0.52. 

Exercise - 5(B) | Q 5 | Page 117

Calculate the mass of a body whose volume is 2 m3 and relative density is 0.52. 

Exercise - 5(B) | Q 6 | Page 117

Calculate the mass of air in a room of dimensions 4.5 m × 3.5 m × 2.5 m if the density of air at N.T.P. is 1.3 kgm-3 . 

Exercise - 5(B) | Q 6 | Page 117

Calculate the mass of air in a room of dimensions 4.5 m × 3.5 m × 2.5 m if the density of air at N.T.P. is 1.3 kgm-3 . 

Exercise - 5(B) | Q 7 | Page 117

A piece of stone of mass 113 g sinks to the bottom in water contained in a measuring cylinder and water level in cylinder rises from 30 ml to 40 ml. Calculate R.D. of stone.

Exercise - 5(B) | Q 7 | Page 117

A piece of stone of mass 113 g sinks to the bottom in water contained in a measuring cylinder and water level in cylinder rises from 30 ml to 40 ml. Calculate R.D. of stone.

Exercise - 5(B) | Q 8 | Page 117

A body of volume 100 cm3 weighs 1 kgf in air. Find: (i) Its weight in water and (ii) Its relative density. 

Exercise - 5(B) | Q 8 | Page 117

A body of volume 100 cm3 weighs 1 kgf in air. Find: (i) Its weight in water and (ii) Its relative density. 

Exercise - 5(B) | Q 9 | Page 117

A body of mass 70 kg, when completely immersed in water, displaces 20,000 cm3 of water. Find: (i) The weight of body in water and (ii) The relative density of material of the body. 

Exercise - 5(B) | Q 9 | Page 117

A body of mass 70 kg, when completely immersed in water, displaces 20,000 cm3 of water. Find: (i) The weight of body in water and (ii) The relative density of material of the body. 

Exercise - 5(B) | Q 10 | Page 117

A solid weighs 120 gf in air and and 105 gf when it is completely immersed in water. Calculate the relative density of solid. 

Exercise - 5(B) | Q 10 | Page 117

A solid weighs 120 gf in air and and 105 gf when it is completely immersed in water. Calculate the relative density of solid. 

Exercise - 5(B) | Q 11 | Page 117

A solid weighs 32 gf in air and 28.8 gf in water. Find: (i) The volume of solid, (ii) R.D. of solid and (iii) The weight of solid in a liquid of density 0.9 g cm-3. 

Exercise - 5(B) | Q 11 | Page 117

A solid weighs 32 gf in air and 28.8 gf in water. Find: (i) The volume of solid, (ii) R.D. of solid and (iii) The weight of solid in a liquid of density 0.9 g cm-3. 

Exercise - 5(B) | Q 12 | Page 117

A body weighs 20 gf in air and 18.0 gf in water. Calculate the relative density of the material of the body. 

Exercise - 5(B) | Q 12 | Page 117

A body weighs 20 gf in air and 18.0 gf in water. Calculate the relative density of the material of the body. 

Exercise - 5(B) | Q 13 | Page 117

A solid weighs 1.5 kgf in air and 0.9 kgf in a liquid of density 1.2 x 103 kg m-3. Calculate R.D. of solid. 

Exercise - 5(B) | Q 13 | Page 117

A solid weighs 1.5 kgf in air and 0.9 kgf in a liquid of density 1.2 x 103 kg m-3. Calculate R.D. of solid. 

Exercise - 5(B) | Q 14 | Page 117

A jeweller claims that he makes ornaments of pure gold that has a relative density of 19.3. He sells a bangle weighing 25.25 gf to a person. The clever customer weighs the bangle when immersed in water and finds that it weighs 23.075 gf in water. With the help of suitable calculations, find out whether the ornament is made of pure gold or not.

[Hint : calculate R.D. of material of bangle which comes out to be 11.6].

Exercise - 5(B) | Q 14 | Page 117

A jeweller claims that he makes ornaments of pure gold that has a relative density of 19.3. He sells a bangle weighing 25.25 gf to a person. The clever customer weighs the bangle when immersed in water and finds that it weighs 23.075 gf in water. With the help of suitable calculations, find out whether the ornament is made of pure gold or not.

[Hint : calculate R.D. of material of bangle which comes out to be 11.6].

Exercise - 5(B) | Q 15 | Page 117

A piece of iron weighs 44.5 gf in air. If the density of iron is 8.9 × 103, find the weight of iron piece when immersed in water.

Exercise - 5(B) | Q 15 | Page 117

A piece of iron weighs 44.5 gf in air. If the density of iron is 8.9 × 103, find the weight of iron piece when immersed in water.

Exercise - 5(B) | Q 16 | Page 117

A piece of stone of mass 15.1 g is first immersed in a liquid and it weighs 10.9 gf. Then on immersing the piece of stone in water, it weighs 9.7 gf. Calculate:

  1. The weight of the piece of stone in air,
  2. The volume of the piece of stone,
  3. The relative density of stone,
  4. The relative density of the liquid.
Exercise - 5(B) | Q 16 | Page 117

A piece of stone of mass 15.1 g is first immersed in a liquid and it weighs 10.9 gf. Then on immersing the piece of stone in water, it weighs 9.7 gf. Calculate:

  1. The weight of the piece of stone in air,
  2. The volume of the piece of stone,
  3. The relative density of stone,
  4. The relative density of the liquid.

Selina solutions for Class 9 Physics Chapter 5 Exercise Exercise - 5(C) [Pages 123 - 124]

Exercise - 5(C) | Q 1 | Page 123

State the principle of floatation. 

Exercise - 5(C) | Q 1 | Page 123

State the principle of floatation. 

Exercise - 5(C) | Q 2 | Page 123

A body is held immersed in a liquid. (i) Name the two forces acting on the body and draw a diagram to show these forces. (ii) State how the magnitudes of two forces mentioned in part (i) determine whether the body will float or sink in liquid when it is released. (iii) What is the net force on the body if it (a) sinks and (b) floats? 

Exercise - 5(C) | Q 2 | Page 123

A body is held immersed in a liquid. (i) Name the two forces acting on the body and draw a diagram to show these forces. (ii) State how the magnitudes of two forces mentioned in part (i) determine whether the body will float or sink in liquid when it is released. (iii) What is the net force on the body if it (a) sinks and (b) floats? 

Exercise - 5(C) | Q 3 | Page 123

When a piece of wood is suspended from the hook of a spring balance, it reads 70 gf. The wood is now lowered into water. What reading do you expect on the scale of spring balance?

Exercise - 5(C) | Q 3 | Page 123

When a piece of wood is suspended from the hook of a spring balance, it reads 70 gf. The wood is now lowered into water. What reading do you expect on the scale of spring balance?

Exercise - 5(C) | Q 4 | Page 123

A solid iron ball of mass 500 g is dropped in mercury contained in a beaker. (a) Will the ball float or sink? Give reasons. (b) What will be the apparent weight of the ball? 

Exercise - 5(C) | Q 4 | Page 123

A solid iron ball of mass 500 g is dropped in mercury contained in a beaker. (a) Will the ball float or sink? Give reasons. (b) What will be the apparent weight of the ball? 

Exercise - 5(C) | Q 5 | Page 123

How does the density ρs of a substance determine whether a solid piece of that substance will float or sink in a given liquid ρL? 

Exercise - 5(C) | Q 5 | Page 123

How does the density ρs of a substance determine whether a solid piece of that substance will float or sink in a given liquid ρL? 

Exercise - 5(C) | Q 6 | Page 123

Explain why an iron nail floats on mercury, but it sinks in water.

Hint : Density of iron is less than that of mercury, but more than that of water. 

Exercise - 5(C) | Q 6 | Page 123

Explain why an iron nail floats on mercury, but it sinks in water.

Hint : Density of iron is less than that of mercury, but more than that of water. 

Exercise - 5(C) | Q 7 | Page 123

A body floats in a liquid with a part of it submerged inside the liquid. (i) Is the weight of floating body greater than, equal to or less than the upthrust?

Exercise - 5(C) | Q 7 | Page 123

A body floats in a liquid with a part of it submerged inside the liquid. (i) Is the weight of floating body greater than, equal to or less than the upthrust?

Exercise - 5(C) | Q 8 | Page 123

A homogeneous block floats on water (a) partly immersed (b) completely immersed. In each case state the position of centre of buoyancy B with respect to the centre of gravity G of the block.

Exercise - 5(C) | Q 8 | Page 123

A homogeneous block floats on water (a) partly immersed (b) completely immersed. In each case state the position of centre of buoyancy B with respect to the centre of gravity G of the block.

Exercise - 5(C) | Q 9 | Page 123

Figure shows the same block of wood floating in three different liquids A, B and C of densities ρ1, ρ2  and ρ3 respectively. Which of the liquid has the highest density? Give a reason for your answer.

Exercise - 5(C) | Q 9 | Page 123

Figure shows the same block of wood floating in three different liquids A, B and C of densities ρ1, ρ2  and ρ3 respectively. Which of the liquid has the highest density? Give a reason for your answer.

Exercise - 5(C) | Q 10 | Page 123

Draw a diagram to show the forces acting on a body floating in water with its some part submerged. Name the forces and show their points of application. How is the weight of water displaced by the floating body related to the weight of the body itself?

Exercise - 5(C) | Q 10 | Page 123

Draw a diagram to show the forces acting on a body floating in water with its some part submerged. Name the forces and show their points of application. How is the weight of water displaced by the floating body related to the weight of the body itself?

Exercise - 5(C) | Q 11 | Page 123

What is the centre of buoyancy? State its position for a floating body with respect to the centre of gravity of the body. 

Exercise - 5(C) | Q 11 | Page 123

What is the centre of buoyancy? State its position for a floating body with respect to the centre of gravity of the body. 

Exercise - 5(C) | Q 12 | Page 123

A balloon filled with helium gas floats in a big closed jar which is connected to an evacuating pump. What will be your observation, if air from the jar is pumped out? Explain your answer. 

Exercise - 5(C) | Q 12 | Page 123

A balloon filled with helium gas floats in a big closed jar which is connected to an evacuating pump. What will be your observation, if air from the jar is pumped out? Explain your answer. 

Exercise - 5(C) | Q 13 | Page 123

A block of wood is so loaded that it just floats in water at room temperature. What change will occur in the state of floatation, if

(a) Some salt is added to water, (b) Water is heated?

Give reasons. 

Exercise - 5(C) | Q 13 | Page 123

A block of wood is so loaded that it just floats in water at room temperature. What change will occur in the state of floatation, if

(a) Some salt is added to water, (b) Water is heated?

Give reasons. 

Exercise - 5(C) | Q 14 | Page 123

A body of volume V and density ρs , floats with volume v inside a liquid of density ρL. Show that `"v"/V = ρ_s/ρ_L` .

Exercise - 5(C) | Q 14 | Page 123

A body of volume V and density ρs , floats with volume v inside a liquid of density ρL. Show that `"v"/V = ρ_s/ρ_L` .

Exercise - 5(C) | Q 15 | Page 123

Two identical pieces, one of ice (density = 900kg per meter cube) and other wood (density = 300kg per meter cube) float on water.

  1. Which of the two will have more volume submerged inside water
  2. Which of two will experience more upthrust due to water.
Exercise - 5(C) | Q 15 | Page 123

Two identical pieces, one of ice (density = 900kg per meter cube) and other wood (density = 300kg per meter cube) float on water.

  1. Which of the two will have more volume submerged inside water
  2. Which of two will experience more upthrust due to water.
Exercise - 5(C) | Q 16 | Page 123

Why is the floating ice less submerged in brine than in water? 

Exercise - 5(C) | Q 16 | Page 123

Why is the floating ice less submerged in brine than in water? 

Exercise - 5(C) | Q 17 | Page 123

A man first swims in sea water and then in river water. (i) Compare the weights of sea water and river water displaced by him.

(ii) Where does he find it easier to swim and why? 

Exercise - 5(C) | Q 17 | Page 123

A man first swims in sea water and then in river water. (i) Compare the weights of sea water and river water displaced by him.

(ii) Where does he find it easier to swim and why? 

Exercise - 5(C) | Q 18 | Page 123

An iron nail sinks in the water while an iron ship floats on water. Explain the reason. 

Exercise - 5(C) | Q 18 | Page 123

An iron nail sinks in the water while an iron ship floats on water. Explain the reason. 

Exercise - 5(C) | Q 19 | Page 124

What can you say about the average density of a ship floating on water in relation to the density of water? 

Exercise - 5(C) | Q 19 | Page 124

What can you say about the average density of a ship floating on water in relation to the density of water? 

Exercise - 5(C) | Q 20 | Page 124

A piece of ice floating in a glass of water melts, but the level of water in the glass does not change.

Give reasons.

Hint: Ice contracts on melting. 

Exercise - 5(C) | Q 20 | Page 124

A piece of ice floating in a glass of water melts, but the level of water in the glass does not change.

Give reasons.

Hint: Ice contracts on melting. 

Exercise - 5(C) | Q 21 | Page 124

A body is held inside water contained in a vessel by tying it with a thread to the base of the vessel. Name the three forces that keep the body in equilibrium, and state the direction in which each force acts. 

Exercise - 5(C) | Q 21 | Page 124

A body is held inside water contained in a vessel by tying it with a thread to the base of the vessel. Name the three forces that keep the body in equilibrium, and state the direction in which each force acts. 

Exercise - 5(C) | Q 22 | Page 124

A loaded cargo ship sails from sea water to river water. State and Explain your observations. 

Exercise - 5(C) | Q 22 | Page 124

A loaded cargo ship sails from sea water to river water. State and Explain your observations. 

Exercise - 5(C) | Q 23.1 | Page 124

Explain the following : 

Icebergs floating in sea are dangerous for ships.

Exercise - 5(C) | Q 23.1 | Page 124

Explain the following : 

Icebergs floating in sea are dangerous for ships.

Exercise - 5(C) | Q 23.2 | Page 124

Explain the following : 

An egg sinks in fresh water, but floats in a strong salt solution.

Exercise - 5(C) | Q 23.2 | Page 124

Explain the following : 

An egg sinks in fresh water, but floats in a strong salt solution.

Exercise - 5(C) | Q 23.3 | Page 124

Explain the following : 

Toy balloons filled with hydrogen rise to the ceiling, but if they are filled with carbon dioxide, then they sink to the floor.

Exercise - 5(C) | Q 23.3 | Page 124

Explain the following : 

Toy balloons filled with hydrogen rise to the ceiling, but if they are filled with carbon dioxide, then they sink to the floor.

Exercise - 5(C) | Q 23.4 | Page 124

Explain the following : 

As a ship in harbour is being unloaded, it slowly rises higher in water.

Exercise - 5(C) | Q 23.4 | Page 124

Explain the following : 

As a ship in harbour is being unloaded, it slowly rises higher in water.

Exercise - 5(C) | Q 23.5 | Page 124

Explain the following : 

A balloon filled with hydrogen rises to a certain height and then stops rising further.

Exercise - 5(C) | Q 23.5 | Page 124

Explain the following : 

A balloon filled with hydrogen rises to a certain height and then stops rising further.

Exercise - 5(C) | Q 23.6 | Page 124

Explain the following : 

A ship submerges more as it sails from sea water to river water.

Exercise - 5(C) | Q 23.6 | Page 124

Explain the following : 

A ship submerges more as it sails from sea water to river water.

Selina solutions for Class 9 Physics Chapter 5 Exercise Exercise - 5(C) [Page 124]

Exercise - 5(C) | Q 1 | Page 124

For a floating body, its weight W and upthrust FB on it are related as :

  • W > FB

  • W < FB

  • W = FB

  • Nothing can be said

Exercise - 5(C) | Q 1 | Page 124

For a floating body, its weight W and upthrust FB on it are related as :

  • W > FB

  • W < FB

  • W = FB

  • Nothing can be said

Exercise - 5(C) | Q 2 | Page 124

A body of weight W is floating in a liquid. Its apparent weight will be

  • Equal to W

  • Less than W

  • Greater than W

  • Zero 

Exercise - 5(C) | Q 2 | Page 124

A body of weight W is floating in a liquid. Its apparent weight will be

  • Equal to W

  • Less than W

  • Greater than W

  • Zero 

Exercise - 5(C) | Q 3 | Page 124

A body floats in a liquid A of density ρ1 with a part of it submerged inside the liquid, while in liquid B of density ρit is totally submerged inside the liquid. The densities ρand ρ2 are related as : 

  • ρ1 = ρ

  • ρ1 < ρ2

  • ρ1 > ρ2

  • Nothing can be said 

Exercise - 5(C) | Q 3 | Page 124

A body floats in a liquid A of density ρ1 with a part of it submerged inside the liquid, while in liquid B of density ρit is totally submerged inside the liquid. The densities ρand ρ2 are related as : 

  • ρ1 = ρ

  • ρ1 < ρ2

  • ρ1 > ρ2

  • Nothing can be said 

Selina solutions for Class 9 Physics Chapter 5 Exercise Exercise - 5(C) [Page 124]

Exercise - 5(C) | Q 1 | Page 124

A rubber ball floats on water with its 1/3rd volume outside water. What is the density of rubber? 

Exercise - 5(C) | Q 1 | Page 124

A rubber ball floats on water with its 1/3rd volume outside water. What is the density of rubber? 

Exercise - 5(C) | Q 2 | Page 124

A block of wood of mass 24 kg floats on water. The volume of wood is 0.032 m3. Find : 

(a) the volume of block below the surface of water , 
(b) the density of wood.
(Density of water = 1000 kg m-3)

Exercise - 5(C) | Q 2 | Page 124

A block of wood of mass 24 kg floats on water. The volume of wood is 0.032 m3. Find : 

(a) the volume of block below the surface of water , 
(b) the density of wood.
(Density of water = 1000 kg m-3)

Exercise - 5(C) | Q 3 | Page 124

A wooden cube of side 10 cm has mass 700 g. What part of it remains above the water surface while floating vertically on water surface? 

Exercise - 5(C) | Q 3 | Page 124

A wooden cube of side 10 cm has mass 700 g. What part of it remains above the water surface while floating vertically on water surface? 

Exercise - 5(C) | Q 4 | Page 124

A piece of wax floats on brine. What fraction of its volume is immersed?

Density of wax = 0.95 g cm-3, Density of brine = 1.1 g cm-3. 

Exercise - 5(C) | Q 4 | Page 124

A piece of wax floats on brine. What fraction of its volume is immersed?

Density of wax = 0.95 g cm-3, Density of brine = 1.1 g cm-3. 

Exercise - 5(C) | Q 5 | Page 124

If the density of ice is 0.9 g cm-3, then what portion of an iceberg will remain below the surface of water in sea? (Density of sea water = 1.1 g cm-3) 

Exercise - 5(C) | Q 5 | Page 124

If the density of ice is 0.9 g cm-3, then what portion of an iceberg will remain below the surface of water in sea? (Density of sea water = 1.1 g cm-3) 

Exercise - 5(C) | Q 6 | Page 124

A piece of wood of uniform cross section and height 15 cm floats vertically with its height 10 cm in water and 12 cm in spirit. Find the densities of wood and spirit. 

Exercise - 5(C) | Q 6 | Page 124

A piece of wood of uniform cross section and height 15 cm floats vertically with its height 10 cm in water and 12 cm in spirit. Find the densities of wood and spirit. 

Exercise - 5(C) | Q 7 | Page 124

A wooden block floats in water with two-third of its volume submerged. (a) Calculate the density of wood.  (b) When the same block is placed in oil, three-quarters of its volume is immersed in oil. Calculate the density of oil. 

Exercise - 5(C) | Q 7 | Page 124

A wooden block floats in water with two-third of its volume submerged. (a) Calculate the density of wood.  (b) When the same block is placed in oil, three-quarters of its volume is immersed in oil. Calculate the density of oil. 

Exercise - 5(C) | Q 8 | Page 124

The density of ice is 0.92 g cm-3 and that of sea water is 1.025 g cm-3. Find the total volume of an iceberg which floats with its volume 800 cm3 above water. 

Exercise - 5(C) | Q 8 | Page 124

The density of ice is 0.92 g cm-3 and that of sea water is 1.025 g cm-3. Find the total volume of an iceberg which floats with its volume 800 cm3 above water. 

Exercise - 5(C) | Q 9 | Page 124

A weather forecasting plastic balloon of volume 15 m3 contains hydrogen of density 0.09 kg m-3. The volume of an equipment carried by the balloon is negligible compared to its own volume. The mass of an empty balloon alone is 7.15 kg. The balloon is floating in air of density 1.3 kg m-3.

Calculate: (i) The mass of hydrogen in the balloon, (ii) The mass of hydrogen and balloon, (iii) The total mass of hydrogen, balloon and equipment if the mass of equipment is x kg, (iv) The mass of air displaced by balloon and (v) The mass of equipment using the law of floatation. 

Exercise - 5(C) | Q 9 | Page 124

A weather forecasting plastic balloon of volume 15 m3 contains hydrogen of density 0.09 kg m-3. The volume of an equipment carried by the balloon is negligible compared to its own volume. The mass of an empty balloon alone is 7.15 kg. The balloon is floating in air of density 1.3 kg m-3.

Calculate: (i) The mass of hydrogen in the balloon, (ii) The mass of hydrogen and balloon, (iii) The total mass of hydrogen, balloon and equipment if the mass of equipment is x kg, (iv) The mass of air displaced by balloon and (v) The mass of equipment using the law of floatation. 

Chapter 5: Upthrust in Fluids, Archimedes’ Principle and Floatation

Exercise - 5(A)Exercise - 5(B)Exercise - 5(C)

Selina Selina ICSE Concise Physics Class 9

Selina ICSE Concise Physics for Class 9 - Shaalaa.com

Selina solutions for Class 9 Physics chapter 5 - Upthrust in Fluids, Archimedes’ Principle and Floatation

Selina solutions for Class 9 Physics chapter 5 (Upthrust in Fluids, Archimedes’ Principle and Floatation) include all questions with solution and detail explanation. This will clear students doubts about any question and improve application skills while preparing for board exams. The detailed, step-by-step solutions will help you understand the concepts better and clear your confusions, if any. Shaalaa.com has the CISCE Selina ICSE Concise Physics for Class 9 solutions in a manner that help students grasp basic concepts better and faster.

Further, we at Shaalaa.com provide such solutions so that students can prepare for written exams. Selina textbook solutions can be a core help for self-study and acts as a perfect self-help guidance for students.

Concepts covered in Class 9 Physics chapter 5 Upthrust in Fluids, Archimedes’ Principle and Floatation are Buoyancy, Archimedes' Principle, Floatation - Principle of Floatation, Relation Between the Density of a Floating Body, Determination of Relative Density of a Solid, Change of Pressure with Depth, Transmission of Pressure in Liquids, Pascal's Law, Atmospheric Pressure, Buoyancy, Archimedes' Principle, Floatation - Principle of Floatation, Relation Between the Density of a Floating Body, Determination of Relative Density of a Solid, Introduction of Fluid.

Using Selina Class 9 solutions Upthrust in Fluids, Archimedes’ Principle and Floatation exercise by students are an easy way to prepare for the exams, as they involve solutions arranged chapter-wise also page wise. The questions involved in Selina Solutions are important questions that can be asked in the final exam. Maximum students of CISCE Class 9 prefer Selina Textbook Solutions to score more in exam.

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