Sections

Key Terms

Key Terms

binding energy: the energy equivalent of the difference between the mass of a nucleus and the masses of its nucleons

ether: scientists once believed there was a medium that carried light waves; eventually, experiments proved that ether does not exist

frame of reference: the point or collection of points arbitrarily chosen, which motion is measured in relation to

general relativity: the theory proposed to explain gravity and acceleration

inertial reference frame: a frame of reference where all objects follow Newton’s first law of motion

length contraction: the shortening of an object as seen by an observer who is moving relative to the frame of reference of the object

mass defect: the difference between the mass of a nucleus and the masses of its nucleons

postulate: a statement that is assumed to be true for the purposes of reasoning in a scientific or mathematic argument

proper length: the length of an object within its own frame of reference, as opposed to the length observed by an observer moving relative to that frame of reference

relativistic: having to do with modern relativity, such as the effects that become significant only when an object is moving close enough to the speed of light for $γ$ to be significantly greater than 1

relativistic energy: the total energy of a moving object or particle $E = γ m c^{2},$ which includes both its rest energy mc² and its kinetic energy

relativistic factor: $γ = \frac{1}{\sqrt{1 - \frac{u^{2}}{c^{2}}}}$ , where u is the velocity of a moving object and c is the speed of light

relativistic momentum: p = γmu, where $γ$ is the relativistic factor, m is rest mass of an object, and u is the velocity relative to an observer

relativity: the explanation of how objects move relative to one another

rest mass: the mass of an object that is motionless with respect to its frame of reference

simultaneity: the property of events that occur at the same time

special relativity: the theory proposed to explain the consequences of requiring the speed of light and the laws of physics to be the same in all inertial frames

time dilation: the contraction of time as seen by an observer in a frame of reference that is moving relative to the observer