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1 vote

Assuming the photon has a moving mass, why current quantum mechanics is unable to prove or deny it?

This question has been beat to death here, a quick search should give you more details. So, in a nutshell: Non-relativistic quantum mechanics doesn't describe massless particles well. In a ...
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0 votes

Force of an accelerating ball?

But if I were to drop the same ball from a greater height, why would it hit the ground harder, with greater force? Yes, it's right. Because when the ball falls from a greater height it has more ...
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0 votes

Force of an accelerating ball?

At the exact moment of impact, is the ball still in free-fall? Is there not a change in momentum due to something other than gravity during the impact? The velocity changes over some (probably very ...
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1 vote

Force of an accelerating ball?

Newtons second law actually states that force on a body is the "rate of change of momentum". So if a ball is dropped from a greater height, it has more velocity as compared to it being ...
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15 votes
Accepted

Do electrons have inertia?

Inertia is the resistance of any physical object to a change in its velocity. This includes changes to the object's speed, or direction of motion. An aspect of this property is the tendency of objects ...
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1 vote

Do electrons have inertia?

Despite quantum effects an electron without external forces will act as any other macroscopic object without external forces. In particular it will not accelerate by itself and it has constant inertia....
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3 votes

Do electrons have inertia?

In physics, the phenomenon of inertia is in a category where an exhaustive explanation for it is not available (and may never be). The point is: in order to have a theory of physics at all the ...
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2 votes

What would be the value of $c$ where $c$ is the speed of light?

The full equation is $$E^2 = (m_{0}c^2)^2 + (pc)^2$$ For light, $m_{0} = 0$, then $E = pc$ The momentum of light is non zero, which can either be derived from photons, or electromagnetic theory. If $...
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-4 votes

What would be the value of $c$ where $c$ is the speed of light?

Different meanings of the word "mass". Revisionists have redefined "mass" to mean "rest mass", thus sowing massive confusion. The photon has no rest mass. In revisionist ...
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4 votes
Accepted

How does massless particles arise in string theory when it starts with the assumption that all strings are composed of massive little pieces?

Susskind corrects himself at 1:00:08 where he says that the "mass density" coefficient in front of the $\dot{X}^2$ term is a non-relativistic analogue; it is not actually a mass-density of ...
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2 votes

How does massless particles arise in string theory when it starts with the assumption that all strings are composed of massive little pieces?

Here is a somewhat hand waving explanation that I think is appropriate given the nature of the question. The equations for the positions of the little masses along the string is essentially a wave ...
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2 votes

Extension in Massive Springs under gravity

The trick is to evaluate the load situation of a slice of lenght $\Delta h$. As it is at rest, the downward force at the bottom of the slice $(F_h)$, plus the weight of the slice must be equal to the ...
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1 vote

What is the general dependence of volume change from mass change due to general relativity?

That means ΔV increases linearly with M. Now, I'm wondering whether this is valid in general or only regarding the earth? Is that ("ΔV increases linearily with M") an inference out of ...
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0 votes

Effect of object mass in coeficient of restitution

The coefficient of restitution of the ball can be expressed as the ratio of momenta before and after impact. Since the mass of the ball does not change, it cancels out leaving only the ratio of ...
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0 votes

Effect of object mass in coeficient of restitution

The masses affect the magnitude of impulse in a collision. Consider two bodies of mass $m_1$ and $m_2$ about to collide with relative velocity $v_{\rm rel} = v_2 - v_1$. Considering the coefficient of ...
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0 votes

Why does Newton's second law involve mass?

Mass requires input of energy to accelerate...Newton's second law is a description of the changes that a force can produce on the motion of a body, not what the body adheres to on the substantive ...
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1 vote

Why does Newton's second law involve mass?

Newton's second law states that the force experienced by a body is vectorially equal to the rate of change of its momentum which is defined as mv. For a fixed mass, this rate reduces to the familiar ...
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0 votes

Nuclear fusion mass defect and energy production

. . . . . which in turn increases the binding energy between the nucleons. What is the origin of this extra energy? What is the cause of this energy?. I think you have misunderstood the idea of ...
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1 vote

Nuclear fusion mass defect and energy production

This answer and the accompanying discussion may be helpful to you https://physics.stackexchange.com/a/667132/313823 It is really no different from a chemical reaction like $$H+OH \longrightarrow H_2O ...
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2 votes
Accepted

Kinetic energy of quarks and mass of proton

I assume the energy carried by the gluons is referring to the binding energy of the three quarks by the strong force. It is more complicated than this. See how the strong interaction is figuratively ...
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  • 221k
0 votes
Accepted

A ball of mass 22g moves to the left at a speed of 35 m / s

Use the work-energy theorem. The work-energy theorem says that the work done on a body by external forces on it is equal to the change in the kinetic energy of the body. Recall that kinetic energy ...
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1 vote

Fusion energy origin

The helium nucleus (for instance) has 2 protons and no neutrons-the mass remains the same, so why did the mass defect occur? Helium nucleus contains two protons and one or two neutrons (depending on ...
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0 votes

Abraham-Lorentz force/electromagnetic mass/relativistic mass

Aka, charged objects seem to have more inertial mass, than neutral objects. This idea is confirmed by experiments done by Thomson What does "charged objects have more mass than neutral ones&...
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1 vote

Abraham-Lorentz force/electromagnetic mass/relativistic mass

If a body is un charged, how do we know that the same rules apply? As for a neutral object, we cannot test whether or not maxwells equations apply. We can, and all experiments are consistent with ...
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4 votes

Abraham-Lorentz force/electromagnetic mass/relativistic mass

First, the concept of relativistic mass has been discarded by the scientific community for decades now. Einstein wrote against using the concept back in 1948. Okun was particularly strong against the ...
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2 votes
Accepted

Is gravity a direct result of Lorentz Contraction?

No. Special relativity on its own doesn't imply general relativity. It's not enough to have some invariance principles; you need to "turn on" mass-energy gravitating by specifying how they ...
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6 votes

Would you run faster on Mars?

Summary All else being equal, runners on Earth will accelerate harder up front, but runners on Mars will have higher top speeds. As such, longer runs will favor Mars, while shorter runs will favor ...
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5 votes

Would you run faster on Mars?

This is a partial answer. Anyone who has run on an Alter-G treadmill will tell you that it is much easier to run at a given speed when your weight is artificially reduced in the way that Alter-G's do. ...
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0 votes

What is the mass of collective oscillations?

My naïve guess would be that it has something to do with a derivative of the dispersion relationship similar to the effective mass of Bloch electrons, but I haven't seen a definitive answer. This is ...
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0 votes

Would you run faster on Mars?

(a fork of Carl’s answer) Your question is interesting but perhaps a bit ill-posed. Consider, for example, the difference between a 100-m sprinter and a marathoner or jogger. The sprinter will lean as ...
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6 votes

Would you run faster on Mars?

You question is interesting but perhaps a bit ill-posed. Consider, for example, the difference between a 100-m sprinter and a miler. The sprinter will lean as far forwards as possible so as to ...
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25 votes
Accepted

Would you run faster on Mars?

The speed of walking and running depend on pendulum-like motion of the legs. If you walk at different speeds the power used varies, and has a minimum roughly corresponding to the free pendulum motion ...
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12 votes

Would you run faster on Mars?

Buoyancy is not what slows the motion of astronauts on the Moon. Buoyancy requires some heavier-than-you liquid to surround you (in order to impede you significantly). When vacuum surrounds you there'...
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0 votes

Why relativistic mass of a body increases with its speed?

The abrupt answer to your question is: because you defined it that way. The arrogant answer: no physicist uses relativistic mass. The useful answer: relativistic mass is really not a useful quantity, ...
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2 votes
Accepted

Why relativistic mass of a body increases with its speed?

I mean, "why" is a fun question because you're eventually destined to just get an "because the universe says so" answer, but I'll try and give the shortest, most intuitive ...
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0 votes

Conservation of mass from material derivative

Both forms are perfectly consistent in the particular case that the divergence of the 3-D vector field is zero. Recall, that the mass continuity equation can also be written as: $$\frac{D\rho}{Dt}=-\...
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7 votes

Why relativistic mass of a body increases with its speed?

I suggest you think of it in the following way... Newton's laws tell us that when you apply a force to an object, the resulting acceleration is inversely proportional to the mass of the object. So you ...
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3 votes

Why relativistic mass of a body increases with its speed?

Special relativity was originally proposed by Albert Einstein in a paper published on 26 September 1905 titled "On the Electrodynamics of Moving Bodies". The incompatibility of Newtonian ...
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15 votes

Why relativistic mass of a body increases with its speed?

Let's rewrite this using $E=mc^2$ to show how the energy increases with velocity \begin{equation} E = m c^2 = \frac{m_0 c^2}{\sqrt{1-\frac{v^2}{c^2}}} \end{equation} Hopefully it is intuitive that the ...
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