Why doesn't the Earth collide with the Sun?

In summary: The point of centripetal, gravitational, and other forces is to keep an object in motion. Without them, an object would just stay at a constant velocity in a straight line.
  • #1
porky
1
0
I am in AP Physics and we just got done with Centripetal force and Universal Gravitation. I was wondering since for the planets to stay in motion they need to have the same force as the object they are orbiting around. Since a bigger mass means a bigger force, how does the Earth stay in motion around the Sun.
 
Physics news on Phys.org
  • #2
I'm not sure I understand your point. Consider a planet in circular orbit about the Sun. The force needed to maintain the orbit equals mv2/r (the "centripetal" force), so the more massive the planet the greater the force needed. But gravity is proportional to mass, so it works out just right.
 
  • #3
also, technically the sun and Earth are both revolving around one another, which may be a helpful way of seeing the situation.
or not.
 
  • #4
I wouldn't look at it like that, that just leads to confusion in my opinion.

Newtons first law states an object will remain still or continue at a constant velocity in a straight line unless acted on by an unbalanced force.

Think of the Earth as originally moving in a straight line, the gravitational force of the sun acted on it, but not enough to pull it straight into it, it pulled it around in a curve, and the velocity stays great enough that it will keep going round and round.

Think of a hammer throw, the object is getting pulled but not enough to go straight to the center, only enough to move in a circle.
 
  • #5
porky said:
Why doesn't the Earth collide with the Sun?
Because it is not in the way.
 
  • #6
A.T. said:
Because it is not in the way.
That's the best answer so far! :smile:
 
  • #7
No force needed to stay in motion.

The Earth orbits the Sun in high vacuum. So there's very little resistance if any to slow Earth's orbit significantly in its billion years existence.
 
  • #8
crapworks said:
No force needed to stay in motion.
You might want to rethink that. It's the gravitational attraction of the Sun on the Earth which allows the Earth to remain in orbit. If there were no force, the Earth would take off in a straight line.
 
  • #9
I have definitely misunderstood the first post!

I was thinking since Porky had just gone through centripetal, etc. what's the point of asking the obvious. I thought he's looking for something else:!)
 
  • #10
Also realize that this thread is almost a year old. That ship has sailed and porky is long gone.
 

Related to Why doesn't the Earth collide with the Sun?

1. Why doesn't the Earth get pulled into the Sun due to its gravity?

The Earth and the Sun have different masses, and the force of gravity is directly proportional to the mass of the objects. The Sun's mass is much larger than the Earth's, so the Earth experiences a smaller gravitational force towards the Sun. Additionally, the Earth is constantly moving in its orbit around the Sun, which creates a balance between the pull of gravity and the centrifugal force.

2. How does the distance between the Earth and the Sun affect their gravitational attraction?

The distance between two objects also plays a crucial role in determining the strength of their gravitational pull. The farther apart two objects are, the weaker their gravitational attraction will be. The Earth and the Sun are approximately 93 million miles apart, which is the perfect distance for the Earth to maintain its stable orbit without getting pulled into the Sun.

3. Why do other planets in our solar system also not collide with the Sun?

The same principles of mass and distance apply to all the planets in our solar system. Each planet has its own unique orbit and distance from the Sun, which allows them to maintain their stable positions. The gravitational pull of the Sun affects all the planets, but their individual masses and distances determine their specific orbits.

4. What would happen if the Earth's orbit was disrupted and it started moving closer to the Sun?

If the Earth's orbit was disrupted and it started moving closer to the Sun, it would experience a stronger gravitational pull. This would cause the Earth to accelerate towards the Sun, ultimately resulting in a collision. However, it is highly unlikely that the Earth's orbit will be disrupted without any external influences.

5. Is there a possibility of the Earth and the Sun colliding in the distant future?

No, the Earth and the Sun are not expected to collide in the distant future. The Sun is expected to expand into a red giant in about 5 billion years, which will engulf Mercury and Venus but leave the Earth relatively unscathed. Even after the Sun dies, the Earth's orbit will not change significantly, and it will continue to revolve around the Sun as a white dwarf star.

Similar threads

B 'A Brief History of Time' question on gravity
    • Other Physics Topics
Replies
4
Views
1K
B Why does the Sun need sunlight?
    • Other Physics Topics
Replies
3
Views
2K
B Understanding gravity: mass and gravity relation
    • Other Physics Topics
Replies
7
Views
14K
B The Sun's Influence on the Moon's Orbit: Is it Negligible?
    • Classical Physics
Replies
4
Views
757
B Why the Earth moves around the Sun forever and ever and ever?
    • Other Physics Topics
Replies
16
Views
2K
Stargazing Does an Analemma visualize the Earth's actual orbit around the sun?
    • Astronomy and Astrophysics
Replies
4
Views
1K
B How quickly does the Earth feel the effects of a halved Sun's mass?
    • Special and General Relativity
2
Replies
38
Views
2K
B Why do we feel gravitational acceleration from the Earth and not from the Sun?
    • Mechanics
Replies
5
Views
1K
B To displace the Earth from its orbit
    • Mechanics
Replies
20
Views
1K
B What is the shape of an asteroid impact on Earth?
    • Classical Physics
Replies
3
Views
978

Hot Threads

Recent Insights

Back
Top