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 5600 km
on a side and 37 km deep and that the rock
has an average mass density of 2800 kg/m3
.
The continent is moving at the rate of about
1.8 cm/year.
What is the kinetic energy of the continent?