What is the relationship between the equation E^2 - p^2c^2 = m^2c^4

In summary, the equation E^2 - p^2c^2 = m^2c^4 is derived from the relationship between rest mass and energy, which can be simplified to E=mc^2. This can also be related to momentum equations such as p=γmv and E=γmc^2. The equation Ev=pc^2 can also be derived using four-vectors.
  • #1
meowchow
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What is the relationship between the equation E^2 - p^2c^2 = m^2c^4 and E = mc^2?
 
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  • #2


meowchow said:
What is the relationship between the equation E^2 - p^2c^2 = m^2c^4 and E = mc^2?

p^2c^2 is the momentum component. An object at rest has 0 momentum, reducing the above to E^2=m^2c^4. Taking the square root of both sides leaves you with the more familiar equation, describing the relationship between rest mass and energy.
 
  • #3


I understand that thank you but I was wondering how you derived that formula using definitions like e=mc^2γ and p^t=mcγ and p^x=mvγ...this is on our physics midterm tomorrow and my friends and I don't understand how to use these definitions to derive the equation
 
  • #4


meowchow said:
I understand that thank you but I was wondering how you derived that formula using definitions like e=mc^2γ and p^t=mcγ and p^x=mvγ...this is on our physics midterm tomorrow and my friends and I don't understand how to use these definitions to derive the equation

Square the energy equation:

E2=m2c4/(1-v2/c2)

Simplify:

E2-E2v2/c2=m2c4

Replace (Ev)2 with (pc2)2:

E2-p2c2=m2c4To get the equation Ev=pc2:

E=γmc2
p=γmv

Eliminate γ & m:

Ev=pc^2**This seems like unnecessary algebra. I don't see why you'd have to derive the above equations from other energy/momentum equations. You should also learn about four-vectors, because the first equation actually comes from the magnitude of the four-momentum.
 
  • #5


Ohh thank you so much! ^____^
 

1. What is the meaning of the equation E^2 - p^2c^2 = m^2c^4?

The equation E^2 - p^2c^2 = m^2c^4 is known as the energy-momentum relation and is a fundamental equation in special relativity. It relates the energy (E), momentum (p), and mass (m) of a particle with the speed of light (c). It shows that energy and momentum are closely linked and that mass can be converted into energy.

2. How is this equation derived?

This equation is derived from Einstein's famous equation E=mc^2, which relates energy and mass. By incorporating the concept of momentum in special relativity, the equation E^2 - p^2c^2 = m^2c^4 is obtained through mathematical manipulation and the use of Lorentz transformations.

3. What does the equation tell us about the nature of matter and energy?

The equation E^2 - p^2c^2 = m^2c^4 shows that matter and energy are not separate entities, but rather two forms of the same thing. It also shows that mass and energy are interchangeable, with mass being a form of energy and vice versa.

4. How does this equation relate to the theory of relativity?

The equation E^2 - p^2c^2 = m^2c^4 is a fundamental part of the theory of special relativity. It is used to describe the behavior of particles at high speeds, where classical mechanics no longer applies. The equation helps to explain the relationship between energy, momentum, and mass in a relativistic framework.

5. What are the practical applications of this equation?

This equation has many practical applications, including in nuclear physics and particle accelerators, where it is used to calculate the energy and momentum of particles. It also has implications in technologies such as nuclear power and nuclear weapons, as it helps to understand the conversion of mass into energy and the release of large amounts of energy from small amounts of matter.

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