Problem
A relatively small impact crater 20 kilometers in diameter could be made by a comet about 2 kilometers in diameter traveling at 32 km/s (32,000 m/s).
Part 1: Assume that the comet has a total mass of 3.6×1012 kilograms. What is its total kinetic energy? (Hint: The kinetic energy is equal to 1/2 mv^2, where m is the comet's mass and v is its speed.) Express your answer to two significant figures and include the appropriate units.
Part 2: Convert your answer from part A to an equivalent in megatons of TNT, the unit used for nuclear bombs. (Hint: One megaton of TNT releases 4.2×10^15 joules of energy.) Express your answer in megatons to two significant figures.