Tides and Moon Gravitational Force

In summary, the Moon creates tides on the seas due to the difference in gravitational field between two points. However, the Moon's gravity affects small stones on land differently than small bits of water in the sea, as the stones are held back by friction while water has low static friction and can easily move. This explains why the Moon does not pull loose stones or other objects lying on Earth as it does with the sea.
  • #1
gianeshwar
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We know Moon creates tides on seas.Then why doesn't Moon pull loose stones or other objects lying loose on earth?
 
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  • #2
gianeshwar said:
We know Moon creates tides on seas.Then why doesn't Moon pull loose stones or other objects lying loose on earth?
It pulls the stone, and the surface under the stone almost equally. The gradient in Moon's gravity is less than the attraction of the stone by the Earth.
 
  • #3
Thanks AT.Why did you use the word gradient?
 
  • #4
Gradient is approximately the difference in gravitational field between two points. The stones are small objects so the moons gravity has the same effect on the whole stone, unlike the ocean. The pull on the ocean "under" the moon is bigger than the pull on the ocean on the opposite side of the earth
 
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  • #5
The difference between small stones on land and small bits of water, in the sea, is that the stones are held back from moving by friction but the static friction in water is very low - so it can move. Try to make a pile of water and then a pile of stones - you will see what I'm getting at.
 
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1. What is the relationship between tides and the gravitational force of the moon?

The gravitational force of the moon plays a major role in creating the tides on Earth. The moon's gravitational pull causes the water on the side of the Earth closest to the moon to bulge out, creating a high tide. At the same time, the water on the opposite side of the Earth is pulled away from the moon, creating a low tide.

2. How does the distance between the moon and Earth affect tides?

The distance between the moon and Earth does affect tides, but it is not the only factor. The closer the moon is to Earth, the stronger its gravitational pull and the higher the tides will be. However, the moon's orbit is not a perfect circle, so the distance varies, causing variations in tide heights.

3. Is the moon the only factor that affects tides?

No, the sun also plays a role in the tides. The sun's gravitational force is about half as strong as the moon's, so it has a smaller effect. However, when the sun and moon are aligned, their gravitational forces combine and create even higher tides, known as spring tides.

4. Can the gravitational force of the moon affect anything other than tides?

Yes, the moon's gravitational force can also affect the Earth's crust. The Earth's crust is not as fluid as water, so it does not create tides, but it can be pulled slightly by the moon's gravitational force. This can cause small changes in the Earth's shape and can also affect the speed of the Earth's rotation.

5. How do tides affect marine life?

Tides have a significant impact on marine life. They play a crucial role in the life cycles of many organisms, such as fish and mollusks. The tides bring in nutrients and food, and also help with reproduction and migration. Changes in tides can also affect the distribution of marine species and their habitats.

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