Astronomy Practice Exam 2026 – Complete Preparation Guide

The equation E = mc² is a fundamental concept in physics that illustrates the mass-energy equivalence principle. This principle states that mass can be converted into energy and vice versa, and this relationship is quantified by the equation itself.

In this equation, E represents energy, m represents mass, and c is the speed of light in a vacuum, which is a very large number (approximately 3 x 10^8 meters per second). The equation essentially means that a small amount of mass can be converted into a vast amount of energy due to the c² term amplifying the mass. This principle is crucial in various fields of physics, including nuclear physics, where it explains how nuclear reactions can release large amounts of energy.

Understanding this relationship is key in appreciating the fundamental nature of energy and mass in the universe, particularly in processes like nuclear fusion in stars, which powers the sun. Thus, the correct answer highlights that the equation fundamentally represents the energy content of mass, demonstrating how mass and energy are interconnected.