Relative Density🔥
The relative density, R.D. (or specific gravity) of a substance is the ratio of the density of the substance to the density of water.

If d= density of substance and dw= density of water,
Relative Density= density/dw
The relative density of water is 1.0.

All metals and most solids have R.D. greater than 1, while air and several liquids have R.D. less than 1.
Units: R.D. bears no units.

Seawater has specific gravity of 1.03. Neglecting the atmospheric pressure, the force exerted by scawater on the hatch door of a submarine of area 0.8 m? at a depth of 300 m is

Let’s attempt this ✨

Oil of mass 0.5 g and relative density 0.5 forms a thin film of area 0.25 m' on the surface of water. The thickness of the oil film is

Attempt everyone ✨

Everyone respond🔥

Upthrust and Archimedes' Principle🔥
An object immersed in a liquid experienccs an upward force which is called the upthrust or buoyancy.

The upthrust is due to the difference in pressure between the upper and the lower faces of the object, the pressure being greater at the lower face.

Archimedes' principle states that a body immersed in a fluid experiences an upward force (upthrust) which is equal to the weight of the fluid displaced.

Any immersed body thus experiences two forces
its true weight(I) acting vertically downward, an
the upthrust (Fu) acting vertically upward.

• It follows that:
(i) an object which is denser than the liquid (d. > dL) has a positive apparent weight, and therefore sinks in the liquid;
(ii)an object which is less dense than the liquid d.< dL)has a negative apparent weight, and rises in the liquid;
(ili)as the object rises to the liquid's surface, the volume of liquid displaced decreases, resulting in a decrease in the upthrust while the true weight remains constant;
(iv) a point is eventually reached at which the upthrust becomes just equal to the true weight, i.e. the apparent weight is zero, and the object floats partially submerged in this position.

This leads to the principle of flotation: a floating body displaces a weight of fluid which is equal to its own weight.

A body which weighs 50 N in air displaces 3.7 kg of water when partially immersed in water. The upthrust on the body is

Attempt everyone ✨

A solid object weighs 750 N in air and 525 N when completely immersed in a liquid of relative density
0.75. The volume of the solid is

Let’s attempt this also✨