Question

A body weight 20n in air and 15n when complete immersed in liquid of density 0.8g/cm3 find upthrust in liquid

Answer 1

Answer:

ANSWER

Upthrust acting on the block in water =15N−12N=3N = ( volume of solid immersed )( density of liquid ) g = V (1) 10 where V is the volume of the block , so V=

10

3

=0.3 cm

3

Block weighs 15N in air implies 15=mg , implies m=

10

15

=1.5g

now density =

volume

mass

=

0.3

1.5

= 5 g/cm

3

so density of block = 5 g/cm

3

hence , relative density of the block = density of block / density of water=

1

5

=5

now Upthrust acting on the block in the liquid =15N−13N=2N= (volume of solid immersed ) ( density of liquid ) g=Vρg=0.3( ρ)g ,

implies ρ of the liquid =

3

2

g/cm

3

so relative density of the liquid = density of liquid / density of water =

1

3

2

=

3

2