Pressure
- Force acting per unit area
- P = Force/Area
- Pressure due to a column of liquid of depth h(without atm pressure) $p = h \rho g$
- Actual press at base of column of fluid $p = h \rho g$ + atmospheric pressure at liquid surface
Upthrust or buoyancy force
- An upward force on a body produced by the surrounding fluid (i.e., a liquid or a gas) in which it is fully or partially immersed, due to the pressure difference of the fluid between the top and bottom of the object
- Net upward buoyancy force is equal to the magnitude of the weight of fluid displaced by the body
- Upthrust = Vρg Or Upthrust = mass of liquid displaced x g = mg
Archimedes’ Principle
- States that the upthrust experienced by an object partially or entirely immersed in a fluid is equal to the weight of the fluid displaced by the object
- Can be applied to objects of all shapes and sizes
- An object floats in equilibrium if the upthrust = weight of object
- An object sinks if upthrust < weight of object
Upthrust (in equilibrium)
= weight of object supported by water/fluid
= weight of fluid displaced
= volume of object submerged in water X density of fluid X g
