**Upthrust in Fluids, Archimedes’ Principle and Floatation Exe-5B** Relative Density and it’s Measurement by Archimedes’ Principle **Long Answer** Type for Class-9 ICSE Concise Physics. There is the solutions of **Long ****Answer** type Questions of your latest textbook which is applicable in 2023-24 academic session**. **Visit official Website CISCE for detail information about ICSE Board Class-9.

**Upthrust in Fluids, Archimedes’ Principle and Floatation Exe-5B Long Answer **

**(ICSE Class – 9 Physics Concise Selina Publishers)**

Board | ICSE |

Class | 9 |

Subject | Physics |

Writer / Publication | Concise selina Publishers |

Chapter-5 | Upthrust in Fluids, Archimedes’ Principle and Floatation |

Exe – 5B | Relative Density and it’s Measurement by Archimedes’ Principle |

Topics | Solution of Exe-5(B) Long Answer Type |

Academic Session | 2023-2024 |

**Exe-5B Relative Density and it’s Measurement Long Answer Type**

**Ch-5 Upthrust in Fluids, Archimedes’ Principle and Floatation Physics Class-9 ICSE Concise**

**Page 129**

**Question 1. **With the use of Archimedes’ principle, state how you will find relative density of a solid denser than water. How will you modify your experiments if the solid is soluble in water?

**Answer:**

Steps:

(i) With the help of a physical balance, find the weight, W_{1} of the given solid.

(ii) Immerse the solid completely in a beaker filled with water such that it does not touch the walls and bottom of beaker, and find the weight W_{2} of solid in water.

**Observations:**

Loss in weight of solid when immersed in water = (W_{1} W_{2}) gf

R.D. = Weight of solid in air/Loss of weight of solid in water

R.D. = W_{1}/(W_{1} W_{2}).

If the solid is soluble in water, then instead of water, take a liquid in which the solid is insoluble and it sinks in the liquid.

Then, R.D. = (Weight of solid in air/Loss of weight of solid in liquid) x R.D. of the liquid.

**Question 2. **Describe an experiment, using Archimedes principle, to find relative density of a liquid.

**Answer:**

Relative density is the ratio of weight of a given volume of liquid to the weight of the same volume of water.

Using Archimedes principle, we can perform an experiment which measures the weight of a liquid displaced by a body and weight of water displaced by the same body.

Weight of liquid displaced by a body is given by the difference of weight of a body in air and weight of a body in liquid.

Weight of the water displaced by the body can be found by knowing the difference of the weight of the body in air and the weight of the body in water.

Therefore, using Archimedes principle, the relative density can be calculated using the formula:

**(Upthrust in Fluids Exe-5B Long ICSE)**

**Question 3. **A body weighs W_{1}gf in air and when immersed in a liquid it weighs W_{2}gf, while it weights W_{3}gf 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.

**Answer:**

(i) Volume of the body = W_{1 }– W_{3 }cm^{3}

(ii) Upthrust due to liquid = loss in weight when immersed in liquid = W_{1} – W_{2 }gf

(iii)

Weight of a body in air = W_{1}gf

and Weight of that body in liquid = W_{2}gf

so Weight of that body in water = W_{3}gf

(iv)

Weight of a body in air = W_{1}gf

and Weight of that body in liquid = W_{2}gf

so Weight of that body in water = W_{3}gf

— : End of **Upthrust in Fluids, Archimedes’ Principle and Floatation** Exe-5B Long Answer Type Solutions :–

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