Question

1. The land area of Greenland is 840,000 mi2, with only 132,000 mi2 free of perpetual ice. The average thickness of this ice is 5000 ft. Estimate the mass  of the ice (assume two significant figures). The density of ice is 0.917 g/cm3.

Answer 1

Area of ice:

$$A=840000-132000=708000\text{ mi}^2.$$

708000 mi² is 1.834·10¹² m².

5000 ft is 1524 m.

The mass of the ice can be approximately found by its thickness and area:

$$m=\rho V=\rho AT=\\ =917·1.834·10^{12}·1524=2.6·10^{18}\text{ kg}.$$