The relativistic momentum and energy of a particle with mass moving with velocity are given by
Learning Goal: To learn to calculate energy and momentum for relativistic particles and, from the relativistic equations, to find relations between a particle's energy and its momentum through its mass.
Find the momentum , in the laboratory frame of reference, of a proton moving with a speed of 0.899 . Use for the mass of a proton.
Express your answer in to three significant figures.
Find the total energy of this proton in the laboratory frame.
Express your answer in millions of electron volts to three significant figures.
What is the value of the expression for this proton?
Express your answer in millions of electron volts squared to three significant figures.
The answer to this part is numerically equal to the rest mass of the proton squared. In fact, this result points to a very important equation in relativistic physics: . This formula indicates an equivalence between mass and energy, which was first realized by Albert Einstein.
Express your answer in to one decimal place.
Thus, if a particle moves at the speed of light, it must have no rest mass. Usually this fact is stated somewhat differently: Massless particles always move at the speed of light. Can you think of an example of such particles?