# Hydrostatics Physics

Hydrostatics Physics

Archimede’s Principle Physics :

• According to the principle when a body ( totally or partially ) immersed in a fluid, it appears to lose a part of its weight and the apparent loss of weight is equal to the weight of fluid displaced.
• Apparent weight of body,
 = Actual Weight of Body – Upthrust = [mg – m / d x ρg] = mg [1 – ρ / d]
• where, d = density of body and ρ = density of fluid.
• Buoyant force depends on the density of the fluid and not on the density of body acting on centre of gravity of fluid. Archimedes Law of Floatation :

• When a body is immersed in a fluid then if :
• The weight W of body is more than the up – thrust W’ ( W > W’ ), the body will sink.
• The weight W of the body is equal to up – thrust W’ (W’ = W), the body floats with whole of its volume inside the liquid.
• The weight ( W < W’ ), the body will float with some of its part outside the liquid.
• When a block of ice floats in a liquid having density greater then that of water, the liquid level rises when all the ice melts into water.
• When an ice block floats in a liquid of density less than that of water, the liquid level falls when all the ice melts into water.
• When an ice block floats in water the water level will remain the same when all the ice melts into water.

Memorable Points :

• Normal atmospheric pressure is equal to 76 cm of height of mercury in the Barometer.
• If h is the barometric height for a liquid of density d, then,
 hdg = 76 x 13.6 x g or h = 76 x 13.6 / d
• Relative Density,
 = Density of Body / Density of Water at 4°C
• A pressure applied at any point of the fluid is equally transmitted in all the directions. 