All Questions
16
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What is a simple example that contradicts the theory that light (photons) could have a super small mass? [duplicate]
The obvious example is that, to bring something that has mass to the speed $c$ requires infinite energy due to special relativity. But what if a kid asked me "What if light/photos had a super ...
- 1,090
0
votes
1
answer
44
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2 Masses on a table confusion - Normal force and weight
Forces up are greater than forces down. However, the masses on the table obviously don't start flying upwards. Am I missing a force here?
- 93
-1
votes
1
answer
61
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How does the collapse of a spherical cloud of point-masses look in the Newtonian framework?
Imagine a spherically symmetric cloud of point masses, without angular momentum, interacting by gravity only.
If we examine this process within a Newtonian framework, the particles accelerate towards ...
- 500
0
votes
2
answers
187
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How could inertial and gravitational mass be even conceptually different?
From https://en.wikipedia.org/wiki/Mass
Although inertial mass, passive gravitational mass and active gravitational mass are conceptually distinct, no experiment has ever unambiguously demonstrated ...
- 105
0
votes
1
answer
107
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Why do I feel a force from a non-accelerating punch? [duplicate]
If I'm getting punched by a fist that is moving at a constant velocity (let's say $20 \mathrm{m/s}$), I still feel a force that is being applied to my body. However, according to $F=ma$, in order to ...
0
votes
1
answer
140
views
Forces on a railway track with curvature and cant (inclined plane)
I'm trying to work out the forces acting on the left and the right rail if the track has curvature and cant (i.e. is an inclined plane)
I've come this far as you see in the picture but I'm struggling ...
- 103
0
votes
1
answer
384
views
Are mass or inertia the same thing, the same properties?
I think so. But I wold like to know another opinions to confirm.
- 441
0
votes
0
answers
94
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Concept of negative mass; gravitational field problems
Almost all of us are acquainted with the problem of calculating the gravitational field inside a bore which is in a solid. Many of the solution manuals I have seen, like to follow the negative mass ...
- 1,228
4
votes
3
answers
580
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What is the connection between inertial/gravitational mass and relativity?
In Einstein/Infield 's The Evolution of Physics (32-35) the authors establish that inertial mass and gravitational mass are the same and then connect this to relativity.Throughout these pages I was ...
- 149
0
votes
2
answers
380
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Concept of mass
In classical mechanics, there seems to be a need to distinguish between inertial and gravitational mass. Some texts show how the concept of mass may be defined with some mathematical rigor. There is ...
- 11
0
votes
2
answers
88
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Acceleration due to gravitational force [duplicate]
I need some help with below. So according to Newton's 2nd law, $a=F/m$, for a given mass, the acceleration depends on mass.
But acceleration due to gravity is independent of mass. There seems some ...
- 1,481
-2
votes
1
answer
340
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Questioning Einstein's view on gravity [duplicate]
Oke, so my mind is blown by Einsteins view on gravity, at least as far as I understand the basics and principles he based his views on.
One of the first things that struck me was that most of his ...
- 637
4
votes
1
answer
2k
views
Reduced mass and energy representation?
If we have a gravitational system where $m<<M$ then we can write down the energy of $m$ as follows:
$$E=\frac{1}{2}m(\frac{dr}{dt})^2+\frac{L^2}{2mr^2}-\frac{GMm}{r}$$
but if $m$ is not small ...
user43487
16
votes
6
answers
24k
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Why can light (photons) bends in a curve through space without mass? [duplicate]
I've heard that light can form a curve if they travel near high-mass stars or even a black hole with strong gravity. Which is according to this Newtonian formula
$$\large F_{g}=\dfrac{Gm_1m_2}{r^2}.$$...
3
votes
1
answer
465
views
How much weight can a person carry to avoid being blown over by wind?
I wonder if there is a certain amount of weight that I could carry in a rolling bag to help prevent me from being knocked over by the wind. I have balance problems and some lack of muscle strength in ...
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