Rest energy

Definition

Rest energy is the energy possessed by an object due to its mass when it is at rest. It is given by the equation $E_0 = mc^2$, where $m$ is the rest mass and $c$ is the speed of light in vacuum.

5 Must Know Facts For Your Next Test

1. Rest energy demonstrates the equivalence of mass and energy as proposed by Einstein's theory of relativity.
2. The formula for rest energy, $E_0 = mc^2$, shows that even a small amount of mass can be converted into a large amount of energy due to the factor of $c^2$ (approximately $9 \times 10^{16} \text{m}^2/\text{s}^2$).
3. Rest energy is a scalar quantity and does not depend on the object's motion or reference frame.
4. In nuclear reactions, a small loss in mass results in a significant release of energy, illustrating the concept of rest energy.
5. Understanding rest energy is crucial for explaining phenomena such as particle-antiparticle annihilation, where two particles destroy each other and convert their rest masses into pure energy.

Review Questions

• What equation represents rest energy and what do each of its terms represent?
• How does the concept of rest energy support the principle of mass-energy equivalence?
• Why does rest energy remain constant regardless of an object's state of motion?

Related terms

Relativistic Energy:

The total energy of an object, including both its kinetic and rest energies, given by $E = \gamma mc^2$, where $\gamma$ is the Lorentz factor.

Lorentz Factor:

$\gamma = \frac{1}{\sqrt{1-\frac{v^2}{c^2}}}$, which describes how time, length, and relativistic mass change for an object moving relative to an observer.

Mass-Energy Equivalence: A principle stating that mass can be converted into energy and vice versa, encapsulated by Einstein's equation $E = mc^2$.