Correct Answer to Question 1

A floating object is in equilibrium and so the resultant force on it is zero. For the pieces of ice, the two forces are: its weight downward and the buoyant force upward - and so these two forces must be equal in magnitude.

Archimede's principle tells us that the buoyant force is equal to the weight of the displaced fluid (water).

Therefore, the mass of the ice is equal to the mass of the displaced water. Suppose that the mass of the ice were 100 gm; the mass of the displaced water is also 100 gm and so the volume of the displaced water must be 100 cm³.

When the ice melts, it becomes 100 gm of water and that water occupies a volume of 100 cm³, i.e., just the volume of the displaced water. Thus there's no change in the water level as the ice melts.

Formula Sheet

Question 1

Question 2

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