The stomach's "sinking feeling"

What is the cause of the weird feeling you get in your lower stomach area when you suddenly descend? i.e. a hill, bumpy plane, or roller coaster.

WAG here: Is it some reflexive mechanism to prevent us from urinating?

Gravity baby, gravity. The abdominal organs have more relative freedom of movement than any other area in the body and move noticably with a sudden change in direction or velocity,

That could be it, except I can reproduce the feeling without actually going over a hill. When I’m speeding down the street trying to get the green light, I sometimes get the same feeling in my stomach.

Maybe it’s just because I’ve been conditioned. For example, when I’ve been riding in a car with my eyes closed and gone over a bump, I don’t get the feeling in my stomach: I’ve wasn’t been able to predict it, so my body didn’t create the sensation.

It’s probably our natural tensing reflex to prevent our guts from being being pushed into our ribcage.

Not gravity, Ivick. Inertia.

Newton’s First Law of Motion:

They rest of your answer is correct. This feeling would be produced during acceleration/deceleration in outer space, even in the absence of gravity.


“Believe those who seek the truth.
Doubt those who find it.” --Andre Gide

You’re right of course TT, I was thinking so much about the anatomy that I didn’t think about the physics,
AKA he who must get around to changing his username to an upper case L

I think that its more a no gravity thing. The space people often take a big plane up real high, turn it & presto! No gravity for 25 seconds.

Handy has it, I think. The Vomit Comet travels a parabolic curve, and the peak of the curve, for reasons I have no grasp of whatsoever, causes gravity to apparently no longer apply to those in the plane.

I’ve always reckoned that the ‘losing your stomach’ feeling when going over a bump was the same thing. Sure feels like it sometimes.

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NASA’s KC-135 “Vomit Comet” doesn’t actually “turn off” gravity; it “simulates” weightlessness by traveling a parabola that causes the passengers to achieve apparent weightlessness due to the change of inertia as the plane goes over the top of the parabola. The microgravity attained at the top of the parabola is compensated by the apparent increase in gravity on climbing and descending the parabola.


“Believe those who seek the truth.
Doubt those who find it.” --Andre Gide