Trying to understand this concept

  • Thread starter ccmetz2020
  • Start date
  • Tags
    Concept
In summary, the moon's gravitational pull keeps the earth moving in a circular orbit around the sun, and tides are the result of the moon's varying attractive force on the earth's different parts.
  • #1
ccmetz2020
15
0
If a force is exerted on the Earth by the moon, how come the Earth doesn't move? I don't get how this works with F=ma because shouldn't there be some acceleration caused the moon exerting an equal and opposite force on the earth?
 
Physics news on Phys.org
  • #2
There is a force exerted to the Earth by the moon, but the net force results in the direction of the bigger force exerted to the Earth by the Sun.
 
  • #3
ccmetz2020 said:
If a force is exerted on the Earth by the moon, how come the Earth doesn't move? I don't get how this works with F=ma because shouldn't there be some acceleration caused the moon exerting an equal and opposite force on the earth?

But the Earth DOES move as the result of the moon's attractive force.

Two objects attracting each other through the force of gravitation will typically orbit around their common center of mass.

Because the Earth is so much more massive than the Moon, it will go in an orbit of tiny extent around the center of mass, whereas the Moon will go in a fairly large orbit.

(The Sun complicates this simplified picture!)

The same holds true for a star with respective to a planet around it.
The star will WOBBLE a bit, as the result of the planet's effect on it, and this WOBBLING is detectable in how the wavelengths of the light emitted by the star looks like.

This is, in fact, the major means at our disposal to discover planets orbiting other stars in the universe.
 
  • #4
Furthermore, the most spectacular effect of the Moon's attractive effect on the Earth are the tides.

The "loose" water facing the Moon is attracted more strongly than the Earth center, whereas the "loose" water on the backside of the Earth is attracted more weakly than the Earth's centre.

Therefore, the water's differing acceleration fromthe Earth centre, coupled with that the Earth's crust moves at the same speed as the Earth centre, results in bulges of water, one facing the Moon on one side of the Earth, another tidal bulge on the other side.
 
  • #5
Orbital mechanics are complicated but the basic principle is centripital force. The moon has tangential velocity so it is constantly falling toward the Earth without getting much closer or farther away (it is changing its orbit over very long periods of time, I think, getting farther out).

http://en.wikipedia.org/wiki/Centripetal_force

You can swing a heavy object (carefully) around in a circle to get feel for the pull of the moon on the earth. The pull is necessary to keep the object moving in a circle (or general orbital path in more advanced studies).

Search online for Newton's Cannon to see how Newton compared the moon's orbit to a projectile fired from a mountain on Earth.
 
  • #6
Read up on Earth Moon Barycenter.

The Earth-Moon system rotates around a point 4600 kiliometers from the Earth's center of mass - that's a point 1700km below the Earth's surface.
 
  • #7
Awesome guys! I'll have to read up on some of this stuff! Thanks for the replies!
 

FAQ: Trying to understand this concept

What is the best way to approach understanding a complex scientific concept?

The best way to approach understanding a complex scientific concept is to break it down into smaller, more manageable parts. Start by identifying any key terms or definitions that are crucial to understanding the concept. Then, try to find real-life examples or analogies that can help make the concept more relatable. Finally, practice applying the concept in different scenarios to solidify your understanding.

What should I do if I am struggling to understand a scientific concept?

If you are struggling to understand a scientific concept, don't be afraid to ask for help. Reach out to your peers, professors, or other experts in the field for clarification or additional resources. You can also try finding alternative explanations or demonstrations of the concept, as different approaches may resonate better with you.

How can I ensure that I truly understand a scientific concept?

A good way to test your understanding of a scientific concept is to try explaining it to someone else. If you can effectively convey the concept in your own words and answer any questions they may have, it is a good indication that you have a solid understanding. You can also try testing yourself with practice problems or quizzes related to the concept.

Is it important to understand the underlying principles behind a scientific concept?

Yes, it is important to understand the underlying principles behind a scientific concept. Having a deeper understanding of the fundamental principles allows you to apply the concept in a wider range of scenarios and make connections to other related concepts. It also helps you to think critically and creatively, as you can use your knowledge to solve problems and make new discoveries.

How can I continue to improve my understanding of a scientific concept?

Continuing to learn and explore the concept is the best way to improve your understanding. Stay updated on new research and developments related to the concept, and try to apply it in different contexts. You can also discuss the concept with others and engage in critical thinking and problem-solving activities to deepen your understanding.

Similar threads

A How Does the Sun's Tidal Effect Influence Earth's Rotation and Moon's Orbit?
Replies
9
Views
3K
B Tidal Locking question about the Earth-Moon system
Replies
4
Views
1K
I Is it accurate to say work is motion against an opposing force?
3
Replies
75
Views
3K
B Explaining Variations of Free-Fall Gravity on Earth?
Replies
22
Views
1K
B Action-reaction of a sailing boat and wind
Replies
8
Views
790
Do I exert a force on the moon?
Replies
2
Views
1K
I Is this analogy between Magnetic Force and Gravitational Force accurate in helping to understand what contributes more to a stronger magnetic force?
Replies
11
Views
968
A Normal force and force of friction inside a tube
Replies
2
Views
1K
I Why exactly does the ocean bulge on both sides of the Earth?
Replies
7
Views
2K
B Normal force in case of inclined plane and banked turn
Replies
3
Views
759

Hot Threads

Recent Insights

Back
Top