# Questions tagged [energy-conservation]

The law of conservation of energy, which states that the amount of energy in a system is constant. For questions about Earth's environment, see the climate-science tag instead.

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### Shouldnt it be $\frac{mv^2}{2}$ through out the spring? Why do different $dm$ masses have different velocities?

I don't understand why you need integration in this question. Shouldn't it be $\frac{mv^2}{2}$ throughout the spring? Why do different $\mathrm{d}m$ masses have different velocities? A spring of ...
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### Does it always take the same amount of energy to get from A to B?

Imagine you have a point A and a point B. Does it takes the same amount of joules to travel from A to B no matter how you do it (if in neutral conditions e.g. no wind)? For example, walking, riding a ...
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### COM frame for photons

We know that there is no frame in which the energy of a photon is zero and hence it has zero momentum. But can we find a frame in which the energy of two head on photons is zero, or the center of mass ...
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### Work and energy: law of conservation of energy? [duplicate]

According to the law of conservation of energy: Energy can neither be created nor be destroyed Then how did energy come into existence?
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### Producing Pressurized Hydrogen Underwater Then Using it To Do Work

This is a bit of a weird one but I didn't know where else to ask this. I was recently talking to my brother and he told me about an idea he had talked with his boss about how to create compressed ...
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### Conservation of energy in superconducting transitions with Meissner effect

In Type I superconductors the transition from normal to superconducting state occurs exactly at its transition temperature. Does this mean that we could theoretically use only a little bit of energy ...
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### Can particles gain energy during inelastic collision?

We know that when two particles collides inelastically, the net energy equation is given by $$E_i=E_f+Q$$ where $E_i$ and $E_f$ are initial and final mechanical energies of the particles and $Q$ is ...
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