Jorge Casajus
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What are the physics definitions for time and energy?
4 votes

Time is no more than a coordinate. It could seem as it is special regarding the physical universe in a classical sense, dissociating time and space, but long years of physics develompent and the ...

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Why does the car move faster?
4 votes

You're increasing the pressure of the air on the back of your car, hence forcing it to accelerate!

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How many derivatives for the position of an object?
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3 votes

Yes, it would be $C^\infty$, since at the lowest level the potential of repulsion will follow a $\propto \frac{1}{r^n}$ law and thus, it will be infinitely differenciable except for the value $r=0$, ...

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How is energy conserved in blueshifting?
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2 votes

You're missing momentum conservation... Intuitively, for a body to be moving at a relativistic speed, it must have very low mass, so momentum conservation, even when colliding with a photon, must be ...

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Is contact force repulsive or attractive?
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2 votes

Repulsive. The contact force comes from the electrons in the outer shell of the atoms in the surface of the objects repelling each other, not only electromagnetically, but also because of Pauli's ...

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Energy distorting space
1 votes

Yes of course it can do the same! The realization is pretty simple: Mass and energy... Are the same thing! So basically, whatever property you can assign to mass, you can assign to energy as well. The ...

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Understanding 4-momentum and the Lorentz invariant product
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1 votes

The good thing about 4-vectors is that the inner product between two of them using the proper metric is always preserved, no matter from which reference frame you take it! I don't know how familiar ...

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Is there a gas present in the Martian atmosphere similar to hydrogen?
0 votes

No, unfortunately there's not a hydrogen-like gas in the Martian atmosphere. However, since such atmosphere is mainly composed of CO$_2$, we can approximate in good measure that any lighter gas could ...

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Why do the two relations of Power in a resistive load $P= I^2 R$ and $P = V^2/R$ (Assume Ideal resistances ) seem contradicting in this situation?
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It's not a contradiction! You're just considering two different cases, since it makes a huge different wether you have fixed current or fixed voltage. Now the thing is that if you have fixed voltage, ...

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Alternative form of the geodesic equations
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I ended up finding out myself. After doing some research, I got to check that the covariant derivative of the metric tensor is null, so the operation of raising and lowering indexes with the metric ...

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Why does SHM happen in vacuum?
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It's easy to see why it happens in vacuum: Energy is conservated in absence of external forces. As you can see, if you set a pendulum to a certain height then let it swing, you've given it some ...

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