 # Selina Solutions Class 9 Physics Solutions for Exercise 5A in Chapter 5 - Chapter 5 Upthrust In Fluids Archimedes Principle And Floatation

A body of volume 100cm3 weighs 5kgf 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

Weight of the body in air = 5kgf

The volume of the body =100cm3

Density of the liquid = 1.8 x 103 kgm-3

(i)Upthrust due to liquid = volume of the solid x density of fluid x acceleration due to gravity

= 100 x 10-1 x 1.8 x 10-2 x g

= 0.18kgf

(ii)weight of the body in liquid = weight of the body in air – upthrust

= 5kgf – 0.18 kgf

= 4.82 kgf

Video transcript
"hello students welcome to leader learning this is ashwini i teach science at lado so here in this question we have a body of volume 100 centimeter cube weighs 5 kgf in air it is completely immersed in a liquid of density 1.8 multiplied by tendous power 3 kg per cubic meter find the up thirst due to the liquid and the weight of the body in liquid so here the weight of the body in air is given that is 5 kgf the volume of the body is 100 centimeter cube and the density of liquid is also given that is 1.8 multiplied by 10 square 3 kg per cubic meter so here the density is in meter per cubic meter so we have to convert this volume of body from centimeter to meter so here volume of body is equals to 100 centimeter cubic right so we can convert it as it is 100 multiplied by 10 raised power 6. so for the meters we can write it as 10 power minus 4 meter cube now if i'm talking about the first part to calculate the up thirst due to the liquid so here up thirst is equals to volume of solid volume of solid multiplied by density of fluid okay here i am writing it as density of fluid multiplied by acceleration due to gravity that is represented by g so i am putting the values here that is 10 raised power minus 4 as we convert it in the meter cube multiplied by density is given 1.8 multiplied by 10 is power 3 and the acceleration due to gravity is we can write it as g okay so here we got the answer that is 0.18 g newton now if i'm talking about to convert it in kgf so it is 0.18 kgf so if i'm talking about the second part here okay the second part constitute the weight of the body in liquid so here the second part the weight of the body is equals to weight of body is equals to weight of body in air body in air minus the up thrust okay so here i'm putting the values for the weight of the body in air is given that is 5 kgf minus the up thrust as we have calculated it it is 0.1 kgf so here we got the values that is 4.82 kgf is the weight of the body in liquid so i hope everything is clear to you if you have any doubts then please put it down in the comment section for more such video solutions please subscribe leader learning thank you"
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