The current theory of the structure of the

Earth, called plate tectonics, tells us that the

continents are in constant motion.

Assume that the North American continent

can be represented by a slab of rock 4150 km

on a side and 38 km deep and that the rock

has an average mass density of 2780 kg/m³

.

The continent is moving at the rate of about

1 cm/year.

The mass of the continent is 1.819 x 10²¹, but how do you find the kinetic energy of the continent?

Answer: 91.4 J

Explanation:

Kinetic energy is the energy possessed by a body due to virtue of its motion.

K. E. = 0.5 m v²

Mass of the continent is given, m = 1.819 * 10²¹ kg

Side of the block of continent, s = 4150 km = 4150000 m

Depth of the block of continent, d = 38 km = 38000 m

(Mass = density * volume

m = 2780 kg/m³ * (4150 * 10³ m) ² * 38 * 10³ m = 1.819 * 10²¹ kg)

The continent is moving at the rate of, v = 1 cm / year = 0.01 m / 31556926 s = 3.17 * 10⁻¹⁰ m/s

⇒ K. E. = 0.5 * 1.819 * 10²¹ kg * (3.17 * 10⁻¹⁰ m/s) ² = 91.4 J

Hence, mass of the continent has 91.4 J of kinetic energy.