Questions tagged [escape-velocity]

Questions about the speed at which an object can go to a point at infinity while ending at rest.

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Can a habitable planet be smaller than 0.58 Earth radii?

According to the below image, the lowest escape velocity a planet can have in order to still be able to retain water on its surface and have a temperature above freezing is 6.5 km/s minimum. With ...
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2answers
138 views

What should the mass of a planet be in-order for its escape velocity to be near the speed of light? [duplicate]

What should the mass of a planet be in-order for its escape velocity to be the speed of light? Is it even possible? What will it look like from an outside viewer? Will it even be visible in the human ...
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1answer
113 views

Do Enceladus' geysers fall back to its surface or do they achieve escape velocity?

Enceladus, a moon of Saturn, has a very low surface gravity at 0.114 m/s² or 0.012 g. It has a subsurface ocean of liquid water and is ejecting plumes of it. Does the ejected water eventually fall/...
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123 views

Largest body in the solar system that a baseball thrown by a professional pitcher could escape

What is the largest (most massive) known body in the solar system that a professional pitcher could throw a baseball off of, i.e. that has an escape velocity lower than ~102 MPH? (45.33 m/s)
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Are exoplanets which are above escape velocity of particular interest?

I was perusing the exoplanet database and looking for some of the more extreme orbits, when I happened upon HD 20782 B: http://exoplanets.org/detail/HD_20782_b Which is also listed (in two sentences)...
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1answer
110 views

Could an object, assuming possible, escape black hole by travelling above constant speed? [closed]

I am always hearing that after travelling inside a given BH's event horizon, the escape velocity is greater than c, which makes it impossible to escape. Suppose an ship is inside a BH. Assume it is ...
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2answers
388 views

Does matter accelerate to the speed of light as it approaches the singularity?

$$v_\mathrm e=\sqrt{\frac{2GM}r}$$ If we understand the escape velocity to be the speed needed to escape from the 'surface' of a gravitational object described by the above equation. It is equally ...
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3answers
203 views

Black hole, escape velocity, going up?

I do know nothing can escape a black hole, and I understand popsci explanation of geodesics of space-time around and inside the event horizon. I however have some trouble with following thought ...
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4answers
2k views

What is the escape velocity of our Galaxy relative to?

I've been thinking that everything has a relative escape velocity, if it has Mass, seemingly. You can escape orbit around the earth by accelerating enough. You can escape the orbit of the sun by ...
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1answer
201 views

Is the radius used in the formula for the escape velocity the average radius of the celestial object or the radius at the starting location?

I learnt that the escape velocity is given by $$v_e = \sqrt{\frac{2GM}{r}}$$ Say I want to launch a rocket from the earth into space and want to calculate the escape velocity $v_e$ (I guess without ...
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2answers
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Can I leave a planet without achieving escape velocity?

I know that if you exceed orbital velocity, you will never fall-back to the planet. My question is not about orbits. It's about brute-force propulsion to achieve altitude. I'm using an ...
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2answers
901 views

Can earth escape sun's gravity with the help of a black hole heading towards our solar system?

To escape the Sun's gravity, the Earth would need sufficient amount of energy. Let's say a stellar black hole has entered our solar system and at a certain distance from earth, the black hole exerts ...
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1answer
319 views

How to get from the earth to another planet/ the moon? What happens on the way? [closed]

I have a problem explaining for my students how to get from the earth to the moon? Is there someone who can give a good explanation? I Think these are words that might be included. Escape velocity, ...
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1answer
201 views

Why are the high density regions in outer space black holes?

The escape velocity of an object is given by the following formula. $$v_e=\sqrt{\frac{2GM}{r}}=\sqrt{\frac{2 \mu}{r}}= \sqrt{2gr}$$ As far as I am aware, the mass of the star which formed the black ...
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What happens if you fail to reach escape velocity for the galaxy?

I was listening to Skeptics Guide to the Universe the other day, and Steve Novella mentioned that the escape velocity for the galaxy is 544 km/s. If an object fails to reach escape velocity on Earth, ...