20. The weight of a body in water is one third of its weight in air. T

1.	20. The weight of a body in water is one third of its weight in air. The density of the body is(1) 0.5 g/cm3(3) 2.5 g/cm3(2) 1.5 g/cm(4) 3.5 g/cm3
Answer» the volume of the body =v cm³andthedensityof the body = d gcm⁻³. Theweight of the body in air,Wair= vdgdyne, where g is the acceleration due to gravity. The buoyant force on the body when it is completely immersed is the weight of displaced water,Wbouyant =v x 1 x gdyne. The weight of the body in water, Wwater = Wair - Wbuoyant = vg(d−1)dyne According to the question, Wwater =1/3Wair ⇒vg(d−1) =1/3vdg ⇒d−1 =1/3d ⇒d−d/3= 1 ⇒2d/3= 1 ⇒d=3/2= 1.5 gcm⁻³.

20. The weight of a body in water is one third of its weight in air. The density of the body is(1) 0.5 g/cm3(3) 2.5 g/cm3(2) 1.5 g/cm(4) 3.5 g/cm3

Answer»

the volume of the body =v cm³andthedensityof the body = d gcm⁻³.

Theweight of the body in air,Wair= vdgdyne, where g is the acceleration due to gravity.

The buoyant force on the body when it is completely immersed is the weight of displaced water,Wbouyant =v x 1 x gdyne.

The weight of the body in water, Wwater = Wair - Wbuoyant = vg(d−1)dyne

According to the question, Wwater =1/3Wair

⇒vg(d−1) =1/3vdg

⇒d−1 =1/3d

⇒d−d/3= 1

⇒2d/3= 1

⇒d=3/2= 1.5 gcm⁻³.

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20. The weight of a body in water is one third of its weight in air. The density of the body is(1) 0.5 g/cm3(3) 2.5 g/cm3(2) 1.5 g/cm(4) 3.5 g/cm3

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