# Selina Solutions for Class 9 Physics Chapter 5 - Upthrust In Fluids, Archimedes' Principle and Floatation

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## Selina Solutions for class 9 Physics Chapter 5 – Upthrust In Fluids, Archimedes’ Principle and Floatation

ICSE Class 9 Physics 5 – Upthrust In Fluids, Archimedes’ Principle and Floatation is the fifth chapter covered in the textbook. The different concepts discussed are buoyancy, Archimedes’ principle, floatation, relationship with density, relative density, determination of relative density of a solid.

The chapter provides students with a detailed explanation about concepts such as buoyancy and upthrust, along with different cases, characteristics properties of upthrust, Archimedes’ principle, explanation of different cases with different densities, the concept of relative density, experimental determination of R.D. with different densities.

Floatation, the principle of floatation, the relation between the density of different objects, application to submarine, ship, iceberg, balloons and solutions to simple numerical problems.

List of subtopics covered in Chapter 5 – Upthrust In Fluids, Archimedes’ Principle and Floatation:

 Number Subtopic 5.1 Buoyancy and upthrust 5.2 Characteristic properties of upthrust 5.3 Reason for upthrust 5.4 Upthrust is equal to the weight of the displaced liquid 5.5 Archimedes’ Principle 5.6 Experimental verification of Archimedes’ Principle 5.7 Solid bodies with a density greater than the density of liquid sink while with a density less than the density of the liquid float 5.8 Density 5.9 Relative density 5.10 Determination of relative density of a solid substance by Archimedes’ Principle 5.11 Determination of relative density of a liquid by Archimedes’ principle 5.12 Principle of floatation 5.13 Relation between the volume of the submerged part of a floating body, the densities of liquid and the body 5.14 Applications of the principle of floatation

List of Exercise

 Name of the exercise Number of questions Page number Exercise-5A 39 109 Exercise-5B 34 116 Exercise-5C 35 123

## Selina Solutions for class 9 Physics Chapter 5 – Upthrust In Fluids, Archimedes’ Principle and Floatation

The chapter provides students with a deep understanding of various important concepts revolving around upthrust in fluids. Upthrust is the upward force acting on a body when it is partially or fully immersed in a liquid, it is also referred to as buoyant force. This concept has been demonstrated with the help of various examples.

The next important topic is Archimedes’ Principle and its experimental verification. The concept of density and relative density can be clearly understood by students as it has been aided with sufficient examples and numerical problems along with worked example problems.

Principle of floatation is covered in the third section of the chapter and is elucidated with different applications that are relevant enough from the students’ perspective.

### Key Features of Selina Solutions for class 9 Physics Chapter 5 – Upthrust In Fluids, Archimedes’ Principle and Floatation

• Selina solutions serve as the ultimate study tool for students
• Relevant analogies, usage of simpler terms to explain concepts makes it student-friendly
• Questions have been answered taking into consideration the guidelines provided by the ICSE
• Solutions have been composed from the textbook thereby aligning to the standard study material
• MCQs have been answered along with explanations
• Numericals are solved on the lines of example problems provided in the textbook

## Frequently Asked Questions on Upthrust in Fluids, Archimedesâ€™ Principle and Floatation

Q1

### What is meant by the term buoyancy?

Buoyancy is the property of liquid to exert an upward force on a body immersed in it.

Q2

### Define upthrust?

Upthrust is also known as the buoyant force. It is the upward force acting on a body when it is partially or fully immersed in a liquid.

Q3

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

An upward force, an upthrust is required to keep a block of wood in water as the upthrust due to water on the block when it is completely submerged is much more than its weight.

Q4

### State Archimedesâ€™ principle?

Archimedesâ€™ principle states that when a body is immersed partially or completely in a liquid, it experiences an upthrust which is equal to the weight of the liquid displaced by it.

Q5

### Define the term density?

The density of a substance is its mass per unit volume, i.e., the density of a substance

Q6

### What is the unit of relative density?

Relative density is no unit.