1). The current theory of the structure of the Earth, called plate tectonics, tells us that the continents are in constant motion.?

Question

Assume that the North American continent

can be represented by a slab of rock 5750 km on a side and 26 km deep and that the rock

has an average mass density of 2750 kg/m3

.

The continent is moving at the rate of about

1.2 cm/year.

What is the mass of the continent?

Answer in units of kg.

2.) What is the kinetic energy of the continent?

Answer in units of J.

3.) A jogger (of mass 78 kg) has the same kinetic

energy as that of the continent.

What would his speed be?

Answer in units of m/s.

Answer 1

(1) (5.75E6 m)^2 * (26000 m) * (2750 kg/m^3)

= around 2 x 10^21 kg but use a calculator.

(2) now multiply answer (1) by

0.012 m/(3.15 x 10^7 s)

(3) and now divide answer (2) by 78 kg.