The force on parts of an extended body in a non-uniform gravitational field, due to residual gravitational attraction between the overall effect on the body and the expected effect on the point in question. Tidal forces are most notably in large moons orbiting near their primaries.
Questions tagged [tidal-effect]
413 questions
270
votes
8 answers
Does Earth really have two high-tide bulges on opposite sides?
The bit that makes sense – tidal forces
My physics teacher explained that most tidal effect is caused by the Moon rotating around the Earth, and some also by the Sun.
They said that in the Earth - Moon system, the bodies are in free-fall about each…
Benjohn
- 3,340
82
votes
8 answers
Moon's pull causes tides on far side of Earth: why?
I have always wondered and once I even got it, but then completely forgot. I understand that gravity causes high and low tides in oceans, but why does it occur on the other side of Earth?
Muhammad Umer
- 2,733
63
votes
5 answers
Why is the Moon considered the major cause of tides, even though it is weaker than the Sun?
You have likely read in books that tides are mainly caused by the Moon. When the Moon is high in the sky, it pulls the water on the Earth upward and a high-tide happens. There is some similar effect causing low-tides. They also say that the Sun…
Moctava Farzán
- 1,924
57
votes
9 answers
Are we slightly lighter during the day and slightly heavier at night, owing to the force of the Sun's gravity?
Using $g = \frac{Gm}{r^2}$, the force on a point mass located at 1 AU from the Sun ($m = 2 \cdot 10^{30} \text{ kg}$) is about ~0.006 N/kg.
Does that mean that, e.g., a 70 kg person is ~42g lighter during the day, and ~42g heavier at night? That…
John Feminella
- 755
55
votes
8 answers
Short of collision, can gravity itself kill you?
Imagine that you are falling into object with huge gravity (i.e. black hole) that does not have any atmosphere.
The question is - before you hit the ground, can the gravity itself (which would be extremely huge) kill you? And if so, how exactly that…
libik
- 661
51
votes
3 answers
Are there tides in the atmosphere?
Analogous to the tides of Earths oceans, do the Moon and Sun cause our atmosphere to bulge in what could be described as a low and high tide?
Alex
- 6,105
50
votes
4 answers
Why do some location on Earth have only one tidal maximum per day instead of two?
Most places in the ocean have two high tides and two low tides per "day" (~25 hours). But I remember reading that some locations only have one of each per day.
This answer has some great explanations as well as helpful graphics and links. I'll…
uhoh
- 6,089
39
votes
6 answers
Why aren't satellites disintegrated even though they orbit earth within earth's Roche Limits?
I was wondering about the Roche limit and its effects on satellites.
Why aren't artificial satellites ripped apart by gravitational tidal forces of the earth?
I think it's due to the satellites being stronger than rocks?
Is this true?
Also, is the…
Sykhow
- 741
38
votes
5 answers
Why do tidal waves appear so suddenly in some rivers?
As tide approaches in lower part of some rivers (e.g. Ganges), a several feet high tidal wave enters from the sea against the flow of the river (making a great noise), and the water level suddenly rises as the wave proceeds.
Here is a youtube video…
Archisman Panigrahi
- 3,350
34
votes
3 answers
Why does the Moon face Earth with the same side?
I know that the rotation period of the moon equals its revolution period. It's just so astonishing that these 2 values have such a small difference. I mean, what is the probability of these 2 values to be practically the same? I don't believe this…
Alex
- 505
34
votes
3 answers
Can we run out of gravitational (tidal) energy?
I read an article on energy forms and sources that made me think. Energy comes from somewhere and is limited in various senses. It's most obvious for fuels: we burn coal and oil and at some point we'll have used up all that we have.
We use solar…
user985366
- 616
33
votes
6 answers
Does bottle water rise a little bit on full moon days?
High tides and low tides are caused by the Moon. The Moon's
gravitational pull generates something called the tidal force. The
tidal force causes Earth—and its water—to bulge out on the side
closest to the Moon and the side farthest from the Moon.…
user218113
31
votes
3 answers
When a planet is heated through gravitational pull, where is the energy taken from?
Jupiters moon Io is heated through the gravitational pull of Jupiter, but when Io is heated because of this, where does that energy come from? How does conservation of energy work for this effect, where is energy "lost"?
bogen
- 415
- 4
- 7
29
votes
3 answers
Are tidal power plants slowing down Earth's rotation?
Are tidal power plants slowing down Earth's rotation to the speed of the orbiting moon? (1 rotation per 28 cca days)
Are they vice versa increasing the speed of moon orbiting by generating some waves in gravitation field?
If yes, can you calculate…
daniel.sedlacek
- 1,968
29
votes
1 answer
How can the Moon have such a strong effect on the ocean?
The gravitational acceleration on Earth is approximately $ 10 \mathrm{m}/\mathrm{s}^2 $. Compared to this, the tidal effect of the Moon's gravity gives a local variation in the acceleration of approximately $ 9 \cdot 10^{-7} \mathrm{m}/\mathrm{s}^2…
Matt Cloudy-grid
- 612