E=mc² relates to mass-energy equivalence, primarily relevant in nuclear reactions where a small amount of mass converts to energy, as seen in atomic bombs. However, it does not apply to projectiles or asteroid impacts, where energy calculations are better represented by kinetic energy formulas like E=1/2mv². The discussion clarifies that while E=mc² helped develop atomic weaponry, it is not used to measure the destructive power of asteroids. The misconception about its application in asteroid impacts was addressed, emphasizing the need for accurate understanding of energy conversion in such scenarios. Overall, E=mc² is significant in nuclear physics but not in measuring the impact energy of asteroids.