# Tag Info

## New answers tagged tidal-effect

4

The distance at which the tidal forces froma primary start tearing apart a satellite is known as the Roche limit. In calculating the Roche limit we assume that the yield stress of the rock making up the planet is small compared to the gravitational forces at work so it can be ignored. The question is then simply whether the gravity of the body (in this case ...

1

The difference between your bungee cord analogy and the train is that the bungee cord is secured to the centre of the merry go round while the train is falling freely. So unlike the bungee, the far end of the train is not supporting the weight of the parts of the train nearer the singularity. The tidal acceleration between two points separated by a small ...

0

Basically, it appears that, according to the opinions expressed in the answers in this page, there is a difference between acceleration by a distant gravity field, and acceleration, say, against a wall as we crash with our car. Let me restate the opinions expressed here in this form: we lock a person inside a windowless spaceship, then subject the ...

1

You are correct. The concern over accelerations is with respect to a force applied on the surface of your body. Even with something like a uniform fluid to apply nearly even pressure across the body, your interior will always have density differences. Any density differences will create internal forces when the outside of the body is given a net force. A ...

1

In short, you're correct: it's not the fall (uniform acceleration) that kills you, but the sudden stop at the bottom (large contact acceleration). But just for fun I'll point out that it's not clear what "uniform acceleration" even means. To operationally define (i.e., measure) acceleration you need an accelerometer. An example is a rigid sphere with a ...

0

You will answer your question if you understand inertia: mass tend to oppose resistance to movement. Example: In a lift going upwards e.g., your feet are lifted while your head "wants" to remain at the same place (in a galilean reference frame). In the frame of the lift, everything happens as if a force ($m_\text{head}\ddot x$, roughly) was exerted on your ...

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The principle of equivalence only applies to objects that are "sufficently" small over a timeframe that is also "sufficently" small. In order to feel tidal forces, an object has to have finite size, and if the tidal forces are measurably, then the object is not sufficiently small.

2

There is a difference between "feeling the force" and "being stretched". If you imagine two balls connected by a spring, and falling towards a massive object, then the closer ball will experience a greater force and therefore "accelerate away" from the ball that is further away - the spring between them will stretch, and thus provide a force balance. A ...

1

I have a feeling, that you may be asking whether gravity is a force or an acceleration? In the confines of Newtonian mechanics, it's much better to talk about gravity in terms of acceleration, because point-like, free falling test masses responding to a large, gravitating body do not experience any actual forces acting on them. It's only a slight of hand, ...

8

If you experience such a uniform force, e.g. when an astronaut on a space walk near the ISS (just earth's gravity), you don't experience any forces at all. That's freefall. Even with 10G, you'd experience a rapid freefall, but that is still harmless. It's the hitting the ground which kills you - that's not a uniform force.

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Over long periods gravitational interactions between planets can have a very large effect on their orbits - especially if the planet you are interacting with is Jupiter. Orbits can become "adjusted" into periods which are in resonance with Jupiter's period. It is also possible for a planet to be moved to a completely different part of the Solar System by ...

3

You've asked a very entertaining question, and the answer is not simple. Let's ignore collisions for the moment. The "purest" effect, that is, the one which involves no change on the part of the planet or its sun, is the effect of tidal bulges in the sun. Just as the earth, for instance, is not a perfect sphere due to tidal forces, so the sun is not a ...

1

If you did extend your arm out, you would have indeed changed your angular momentum, and for angular momentum to be conserved your orbit would change slightly in the opposite direction. In addition (I am going by your theory of "partial Spaghettification,"), if your orbit was not thrown off by the gravitational pull of the black hole(which it would be, I ...

3

There's a correct simple answer, a wrong simple answer, and a detailed correct answer. The wrong simple answer is that the Moon raises two bulges in the oceans. The Earth's rotation pulls the bulge closer to the Moon ahead of the Moon angularly, and this in turn results in a transverse acceleration of the Moon. That transverse acceleration in turn causes ...

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