Understanding the Equation E=mc^2 and Its Applications

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In summary, the conversation discusses a question about determining the correct answer to a homework problem related to the rest mass of an object. The answer is C, but the person initially chose A and cannot see why B and D are wrong. The conversation goes on to explain that A is wrong because a proton can have kinetic energy separate from its rest-mass energy, and B and D are wrong because more information is needed to determine the original mass or energy of an object.
  • #1
jsmith613
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Homework Statement


see attached question


Homework Equations





The Attempt at a Solution



I chose A but this is wrong :S - why?

The answer is C but I cannot see why B/D are wrong.
I literally guess A as this was the only time I had used the fomula
 

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  • #2
A is wrong because, for example, a proton can have kinetic energy separate from its rest-mass energy.
 
  • #3
Steely Dan said:
A is wrong because, for example, a proton can have kinetic energy separate from its rest-mass energy.

so why is C correct and B/D wrong?
 
  • #4
jsmith613 said:
so why is C correct and B/D wrong?
First of all, I think A is wrong because there is no change in mass. B is wrong because you cannot determine the original mass of coal from just the rest mass of a proton and rest mass of an electron. You would have to have other information. Similarly with D you would cannot determine the energy from the rest masses of a proton or electron. You would have to know how fast the protons were moving before collision.

AM
 
  • #5
thanks
 

FAQ: Understanding the Equation E=mc^2 and Its Applications

What does the equation E=mc^2 represent?

The equation E=mc^2 represents the relationship between mass and energy, where E represents energy, m represents mass, and c represents the speed of light. It shows that mass and energy are interchangeable and can be converted into one another.

How was the equation E=mc^2 derived?

The equation was first derived by Albert Einstein in his theory of special relativity. He realized that the speed of light is constant and that energy and mass are interconnected, leading to the famous equation.

What are some practical applications of E=mc^2?

One of the most well-known applications of the equation is in nuclear energy. Nuclear reactions convert a small amount of mass into a large amount of energy, as shown by the equation. E=mc^2 has also been used in medical imaging, such as PET scans, and in the development of nuclear weapons.

Does E=mc^2 apply to all forms of energy?

Yes, the equation applies to all forms of energy. This includes kinetic energy, potential energy, thermal energy, and electromagnetic energy. However, it is most commonly used in relation to nuclear energy.

Can E=mc^2 be used to travel faster than the speed of light?

No, the equation does not allow for travel faster than the speed of light. The speed of light is the maximum speed at which anything in the universe can travel, and according to the equation, it would require infinite energy to reach this speed.

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