3) Thanks to recent satellite data, we know that the North American continent is drifting westward at a speed of about 1cm/yr. We can assume that the solid part of a continent is about 50 kilometers thick. Estimate the kinetic energy that the continental US has as a result of this motion. After you have your answer, look up (rather than estimating) actual numbers for mass, distance, etc, and re-calculate the kinetic energy of the continental US to see how close you were