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
- 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.