An aluminium sphere is dipped into water which of the following is tru

1.	An aluminium sphere is dipped into water which of the following is true ?
Answer» BUOYANCY will be less in water at `0^(@)C` than that in water at `4^(@)C`. Buoyancy will be more in water at `0^(@)C` than that in water at `4^(@)C`. Buoyancy in water at `0^(@)C` will be same as that in water at `4^(@)C`. Buoyancy may be more or less in water at `4^(@)C` DEPENDING on the radius of the sphere. SOLUTION :Suppose volume of sphere is V and its density is `sigma` and density of water is `rho` `:.` Mass of sphere `m=Vrho` Bouyant force `F=mg` `F=Vrhog""[becausem=Vxxrho]` `Fprop rho""[because" V and "rho" are constant"]` `:.(F_(4^(@)C))/(F_(0^(@)C))=(rho_(4^(@)C))/(rho_(0^(@)C))` But density of `4^(@)C` temperature water is maximum, `:.rho_(4^(@)C)gtrho_(0^(@)C)rArr(rho_(4^(@)C))/(rho_(0^(@)C))gt1` `:.F_(4^(@)C)/(F_(0^(@)C))gt` `:.F_(4^(@)C)gtF_(0^(@)C)` Hence, Buoyant force in `0^(@)C` water is less than that in `4^(@)C`.

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