Questions tagged [velocity]
Questions regarding the movement of an object at a given speed and direction, often related to the concepts of orbital velocity and escape velocity.
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Why does light accelerate instantaneously to c, while no other phenomena do it? [closed]
In physics, it always takes some time for a particle to move from rest to some speed.
However, photons (light particles) accelerate instantly from zero to c. How? (A visualization would be helpful.)
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Can a planet with no atmosphere be orbited at extremely low altitudes?
Can a planet that has absolutely no atmosphere be orbited by a spacecraft at extremely low "altitudes" (if you'd even call it altitude at such a low orbit.
For instance, if this planet's ...
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How do we calculate the escape velocity of galaxies?
How do we calculate the escape velocity of galaxies?
Do we have to know the total mass?
What is the escape velocity for Milky Way?
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What does the velocity dispersion of a galaxy mean?
Also, what is the advantage of getting information about the velocity dispersion of a galaxy?
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What (actually) is the " deprojected half-light radius" of this almost-all-dark-matter Galaxy?
The recent news of the Ultra Diffuse Galaxy (UDG) Dragonfly 44 is an excellent example of what could be termed 'observe different' thinking. The dragonfly telescope is noted not for the size of its ...
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Why does Gaia use only calcium NIR lines for stellar radial velocity measurements?
I was reading this overview article about the Gaia spacecraft and I saw the following statement:
These spectra provide radial velocity information that are used to study the kinematic and dynamic ...
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Does the escape velocity formula take into account how a gravitationally bound object's distance to its primary increases before coming back down?
Confusing title, I know. Imagine a perfect, homogenous sphere with an exact radius of $1,000 \text{km}$ and an exact mass of $8 \times 10^{15} \text{kg} $.
If you use the formula for escape velocity $...
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Can "rogue" supermassive black holes be made this way?
Could two galaxies (one big and one small)intersect at a velocity to allow the smaller black hole to escape but not the galaxy around it?
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What is the standard reference point for measuring speed?
Speed, as we know, doesn't exist without first having a reference point. We then say that the reference point isn't moving at all, and speed is then measured in relation to the reference point.
What ...
user19
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Which celestial object in the solar system has the fastest tangential velocity at its surface?
Consider all of the naturally-occurring objects in the solar system : in the reference frame of the object's center (ie, ignoring the orbital velocity around the sun or, in the case of satellites, ...
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How to find the shape of an orbit
What is the minimum information I need to be able to draw the shape of an orbit of a body that orbits the sun? With this information how can I figure out the shape of its orbit?
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Are black holes solely responsible for hyper velocity stars?
I read that the stars orbiting around Sagittarius A* (a.k.a the supermassive black hole located at the heart of the Milky Way) move very fast (many times faster than our Sun moves across the galaxy), ...
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Is there a rough analytical expression for the Milky Way's radial mass distribution?
I found the image below in Space.com's article This 3D Color Map of 1.7 Billion Stars in the Milky Way Is the Best Ever Made, although it is not the map mentioned in the title.
The caption for this ...
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Calculating obital velocity from radial velocity
I'm not really a physicist so I don't know if it's possible to get the real orbital velocity of a star from its radial velocity. I'm working on a paper for school and I want to get the mean velocity ...
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Why most planets don't spin retrograde? [duplicate]
Edit: just found duplicate
Since orbital velocity is greater on small orbits, and smaller on large orbits, why don't planets spin retrograde around their own axis?
One portion of planet's mass is ...
user16500