Your weight on Phobos
Your mass does not change when you travel. Your weight does, because weight is a force and it depends on the local gravitational field. Surface gravity here is under a thousandth of Earth. A brisk jump would put you in orbit.
Your weight there, in kilograms-force
0.041
- Your weight as a force
- 0.41
- Your weight in pounds-force
- 0.09
- Surface gravity
- 0.0058 m/s2
- Gravity relative to Earth
- 0.000 59
- How high that jump would take you
- 846.644
- Time for something to fall one metre
- 18.583 s
- Your weight on Earth for comparison
- 686.47
Show the working
- Your mass = 70
- How high you can jump on Earth = 0.5
- gm = 7.11e5 = 711 000
- radius = 1.108e4 = 11 080
- Surface gravity = 711 000 / 11 080^2 = 0.005 791 49
- Gravity relative to Earth = 0.005 791 49 / 9.80665 = 0.000 590 567
- Your weight as a force = 70 * 0.005 791 49 = 0.405 404
- Your weight there, in kilograms-force = 0.405 404 / 9.80665 = 0.041 339 7
- Your weight in pounds-force = 0.405 404 / 4.4482216152605 = 0.091 138 5
- How high that jump would take you = 0.005 791 49 > 0 ? 0.5 * 9.80665 / 0.005 791 49 : 0 = 846.644
- Time for something to fall one metre = 0.005 791 49 > 0 ? sqrt(2 * 1 / 0.005 791 49) : 0 = 18.5832
- Your weight on Earth for comparison = 70 * 9.80665 = 686.466
Values are shown to six significant figures here; the arithmetic itself runs on exact fractions and is only rounded where a number is printed.
Scenarios & local history
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The formula
- surface gravity g = GM / r^2
- weight = mass x g
- jump height scales inversely with gravity for the same take-off energy
The gravitational constant G is the least precisely known fundamental constant, so results here are reported as rounded rather than exact.
Kilograms-force is what a bathroom scale reads. It is a force, not a mass, which is why the number changes and your mass does not.
Surface gravity here is under a thousandth of Earth. A brisk jump would put you in orbit.
Where the numbers come from
- GM and mean radius from planetary ephemeris and spacecraft tracking solutions.