Just as precise measurements are necessary in science, it is equally important to be able to make rough estimates of quantities using rudimentary ideas and common observations. Think of ways by which you can estimate the following (where an estimate is difficult to obtain, try to get an upper bound on the quantity) : (b) the mass of an elephant.
Consider a ship of known base area floating in the sea. Measure its depth d 1 in the sea. The volume of water displaced by the ship: V 1 =Ad. Now, move an elephant on the ship and measure the depth of the ship, d 2 in this case. The volume of water displaced by the ship with the elephant on board: V 2 =Ad 2 . The volume of water displaced by the elephant= Ad 2 −Ad 1 . The density of water=D. Mass of elephant = D×(Ad 2 −Ad 1 )
