Question

Assume that the North American continent can be represented by a slab of rock 4350 km on a side and 36 km deep, and that the rock has an average mass density of 2760 kg/m³. The continent is moving at the rate of about 1.8 cm/year. What is the mass of the continent?

A) 2.43×10²³ kg
B) 3.15×10²³ kg
C) 4.20×10²³ kg
D) 5.12×10²³ kg

Answer 1

The mass of the continent is 1.88 * 10²¹ kg and is none of the above.

How to find the mass from density?

The formula to find the mass here is:

m = ρV = ρa²h

where:

ρ is density

a is length of base

h is height

We are given:

a = 4350 km = 4350000 m

h = 36 km = 36000 m

ρ = 2760 kg/m³

Thus:

m = 2760 * 4350000² * 36000

m = 1.88 * 10²¹ kg