question_answer 26)

                  An aluminium sphere is dipped into water. Which of the following is true?                 (a) Buoyancy will be less in water at \[{{0}^{o}}C\] than that in water at \[{{4}^{o}}C\].                 (b) Buoyancy will be more in water at \[{{0}^{o}}C\] than that in water at \[{{4}^{o}}C\].                 (c) Buoyancy in water at \[{{0}^{o}}C\] will be same as that in water at \[{{4}^{o}}C\].                 (d) Buoyancy may be more or less in water at \[{{4}^{o}}C\] depending on die radius of the sphere.                

Answer:

                  (a) Buoyancy \[={{V}_{\rho g}}\] where \[\rho \] is die density of water. Since density of water at \[{{4}^{o}}C\] is more than its density at \[{{0}^{o}}C\], therefore, buoyancy will be less in water at 0°C than that in water at \[{{4}^{o}}C\].