[Relativity] Energy and momentum question

In summary, the relation between total relativistic energy, mass, and momentum of a particle is given by the equation E^2 = (cp)^2 + (mc^2)^2. Using this equation, we can calculate the momentum and speed of an antiproton with a total energy of 5.00 GeV, given that we know the mass of the proton. However, if the mass is not given, we cannot find a solution as we would need at least one more known value to solve for the momentum or speed.

Homework Statement

Write down a relation between the total relativistic energy, mass and momentum of a
particle. An antiproton has a total energy of 5.00 GeV. Calculate its momentum and its
speed.

Homework Equations

E = γmc^2
E = (cp)^2 +(mc^2)^2
p = γmv

The Attempt at a Solution

I've tried subbing everything in and playing around with the algebra but I can't get an expression entirely in terms of v or p.
Also how do you get the proper math equations on here? Are the tags [itex]?

Last edited:

Homework Statement

Write down a relation between the total relativistic energy, mass and momentum of a
particle. An antiproton has a total energy of 5.00 GeV. Calculate its momentum and its
speed.

Homework Equations

E = γmc^2
E = (cp)^2 +(mc^2)^2
p = γmv

The Attempt at a Solution

I've tried subbing everything in and playing around with the algebra but I can't get an expression entirely in terms of v or p.
Also how do you get the proper math equations on here? Are the tags [itex]?

Here's a TeX tutorial. https://www.physicsforums.com/showpost.php?p=3977517&postcount=3 Try just using the second equation. You know E and you can look up the mass of the proton. That will get you p.

Dick said:
you can look up the mass of the proton

Sorry I should have said, this is a question from an exam a few years ago and it doesn't mention the mass of the proton anywhere in the entire paper. Is there a way to get the answer without knowing m?
Cheers for the tutorial!

Sorry I should have said, this is a question from an exam a few years ago and it doesn't mention the mass of the proton anywhere in the entire paper. Is there a way to get the answer without knowing m?
Cheers for the tutorial!

No, you need to know something else besides just the energy.

Dick said:
Try just using the second equation.

And make that E^2, not E, on the left-hand side.

jtbell said:
And make that E^2, not E, on the left-hand side.

Good point!

What is relativity?

Relativity is a theory developed by Albert Einstein that explains the relationship between space and time. It states that the laws of physics are the same for all observers in uniform motion, and the speed of light in a vacuum is constant for all observers.

What is the equation for energy in relativity?

The equation for energy in relativity is E=mc², where E is energy, m is mass, and c is the speed of light.

How does relativity affect energy and momentum?

According to the theory of relativity, energy and momentum are not conserved separately but are actually components of a single, conserved quantity called four-momentum. This means that when one changes, the other also changes in a way that maintains the overall conservation of four-momentum.

What is the difference between special relativity and general relativity?

Special relativity deals with the laws of physics in inertial frames of reference, while general relativity extends these principles to non-inertial frames, including those affected by gravitational forces. General relativity also accounts for the curvature of spacetime caused by mass and energy.

How has the theory of relativity been proven?

The theory of relativity has been extensively tested and proven through various experiments, such as the Michelson-Morley experiment, which showed that the speed of light is constant for all observers. Other evidence includes the bending of starlight by the sun's gravity and the time dilation observed in high-speed particle accelerators.

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