A sudden decrease of gravity on Earth [closed]
A sudden decrease of gravity on Earth [closed]
I have an idea about a story where gravity suddenly changed and became about 10-20% weaker (lower). Humanity now needs to adapt to the new situation.
What disasters and catastrophes would this sudden change cause on Earth?
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2 Answers
2
Gravity, according to the well known general formula given by Newton, is given by
$ g = const times $$m over distance^2$
Therefore a sudden decrease in the gravitational attraction produced by Earth can only be due to either:
The first one means a big chunk of Earth is gone all of a sudden, while the second one means a big chunk of (light) material is added all of a sudden.
In both cases that is a disaster on its own: it means that some massive object struck Earth and got either splatted on it or broke it apart.
How? Can't it just reduce without any explanation?
– SovereignSun
Sep 2 at 13:07
@SovereignSun, no if you want to stay within the realm of physics.
– L.Dutch♦
Sep 2 at 13:16
@SovereignSun - this question has the 'Reality-Check' tag. This answer is appropriate (excellent) for that tag. If you wish for answers that ignore the cause, remove the tag.
– user535733
Sep 2 at 13:23
Or, under really strange conditions if $G$ is changed. But that would be total collapse of everything existing.
– rus9384
Sep 2 at 18:37
I just want to expand the answer of @L.Dutch.
$$g = G_constant times fracmassradius^2$$
Which in Earth is:
$$(6.6740831 times 10^-11 times fracN times m^2kg^2) times frac5,9736 times 10^24kg6,378,100 m^2 = 9.8004 m/s^2$$
To reduce gravity decreasing mass, we will need this equation:
$$G times frac(5.9736-m_loss) times 10^24 kg6,378,100 m^2 = 9.8004 m/s^2 - (1-g_textloss%)$$
To reduce gravity increasing radius, we will need this equation:
$$G times frac5.9736 times 10^24 kg(6,378,100 + r_gain) m^2 = 9.8004 m/s^2 - (1-g_textloss%)$$
Both scenarios are catastrophes:
I think "massive earthquakes" might even be an understatement. Increasing the sizes of the continents and the oceans between them could be done by expanding the plates, which would put massive stress on them, or by just moving them apart and leaving gaps between them which would be quickly filled by upwelling magma. Either way, it sounds more like a new Hadean Eon than like just a Michael Bay movie.
– abarnert
Sep 2 at 16:52
None that we would be aware of; since we would all be dead.
– steverino
Sep 2 at 14:14