Question

relative density of a substance lighter than water formula .EXPLAIN.

Answer 1

Relative Density is the ratio of a density of a substance to the density of water at 4°C.

So mathematically,

RD = Density of a substance ÷ Density of water at 4 ° C

RD= Mass of a substance ÷ Mass of same volume of water at 4°C

RD = Weight of a substance ÷ Weight of same volume of water at 4°C

Using a RD Bottle, (M3 - M1) ÷ (M2 - M1). Where M1 is the mass of empty bottle, M2 is the mass of bottle + water, M3 is the mass of bottle with the required liquid

Using Archimedes Principle

(Weight of body in air) ÷ ( Weight of body in air - Weight of body in water)

(Weight of body in air ÷ { Weight of body in air - Weight of body in liquid other than water}) × RD of that liquid

The above two calculations of RD is done based on the principle of buoyancy , Archmides principle and Law of Floatation. It states that the loss of weight in a body when immersed in a liquid is equal to the weight of the liquid displaced by the body.

Up thrust = Loss in weight =

= Vol of liquid displaced× Density of liquid × Accelaration due to gravity

= Mass of liquid displaced× Accelaration due to gravity

= Weight of the liquid displaced