• zeromodz
In summary, the equation vescape = √(2GM)/R tells you the escape speed of a object moving away from another object with a certain mass. If the object is a spherical ball, its escape speed is 5.4 x 10-5 m/s.
zeromodz
Okay this equation is giving me some trouble, I just have a question

vescape = √(2GM)/R

Say I wanted to find the escape velocity of myself 3 meters away
So I would use
vescape = √(2)(6.674*10^-11)((145*4.44)/9.8)/(3)
= 5.419003598 *10^-5

So does this mean something that moves that slow cannot escape me farther than 3 meters away?

It doesn't seem right. My gravitational field feels so ephemeral. Is this correct?

Last edited:
I don't know why your mass is 145/9.8 (you weigh only 15 kg?), but yes, your escape velocity is tiny, and yes, something moving slower than your escape velocity can't escape from you in an ideal world. In the real world, turbulence, Brownian motion, and the gravity of other objects make that conclusion moot.

Weight is a force.
F = MA
Therefore
M = F/A or F/G

So I could take my weight in ibs and divide it by 9.8 to get my mass.

zeromodz said:
So I could take my weight in ibs and divide it by 9.8 to get my mass.
Careful! If you knew your weight in Newtons (not pounds), then you could divide by g = 9.8 m/s2 to get your mass in kg. When using equations such as W = mg, you need to use consistent units: in this case, Newtons, kilograms, and m/s2.

Doc Al said:
Careful! If you knew your weight in Newtons (not pounds), then you could divide by g = 9.8 m/s2 to get your mass in kg. When using equations such as W = mg, you need to use consistent units: in this case, Newtons, kilograms, and m/s2.

Okay, thanks a lot. That really messed me up. I changed it, but back to my point. Was my calculations and logic correct?

In theory, if you were isolated in a big region of empty space, and tried to toss say a marble away, it would return to you if the initial velocity were less than escape velocity, or it would go into orbit around you if it had a correct satellite velocity. I think ...

http://en.wikipedia.org/wiki/Escape_velocity

The proper unit for mass in British enegineering is slugs, that is, your weight in pounds force divided by standard gravity 32.174 ft/s/s. Always work in some consistent set of units.

zeromodz said:
Was my calculations and logic correct?
Using your numbers, I get an escape speed of about 5.4 x 10-5 m/s. (So double check your arithmetic.) Which basically says that it doesn't take all that much energy to escape your gravitational field. So if you were in outer space--away from any other masses--and some small object was 3 meters away and moving at less than that speed it could not escape your gravitational field. (But give it the merest push and it's gone!)

Of course, this calculation assumes that you are a spherical ball! (That's how the escape velocity formula is derived.) So I wouldn't take it too seriously.

Doc Al said:
Using your numbers, I get an escape speed of about 5.4 x 10-5 m/s. (So double check your arithmetic.) Which basically says that it doesn't take all that much energy to escape your gravitational field. So if you were in outer space--away from any other masses--and some small object was 3 meters away and moving at less than that speed it could not escape your gravitational field. (But give it the merest push and it's gone!)

Of course, this calculation assumes that you are a spherical ball! (That's how the escape velocity formula is derived.) So I wouldn't take it too seriously.

Thanks, the weight thing in Newtons messed me up. Thank you so much anyways. I understand now.

1. What is escape velocity?

Escape velocity is defined as the minimum velocity required for an object to escape the gravitational pull of a larger body, such as a planet or moon.

2. How is escape velocity calculated?

Escape velocity can be calculated using the equation v = √(2GM/r), where G is the gravitational constant, M is the mass of the larger body, and r is the distance from the center of the larger body to the object.

3. What factors affect escape velocity?

The factors that affect escape velocity include the mass of the larger body, the distance from the center of the larger body, and the gravitational constant.

4. Can escape velocity be achieved on Earth?

Yes, escape velocity can be achieved on Earth. It is approximately 11.2 km/s at the Earth's surface, but this value decreases as distance from the Earth's center increases.

5. Is escape velocity the same for all objects?

No, escape velocity varies depending on the mass and distance of the object from the larger body. For example, the escape velocity from the Moon is much lower than the escape velocity from Earth due to the Moon's lower mass and weaker gravitational pull.

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