Gravity: Need Help Understanding Its Effects

  • Context: High School 
  • Thread starter Thread starter naler62188
  • Start date Start date
  • Tags Tags
    Effects Gravity
Click For Summary

Discussion Overview

The discussion centers around the effects of gravity as one approaches the core of the Earth, exploring whether gravity increases or decreases in that context. Participants examine theoretical implications, logical arguments, and the application of gravitational principles.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant questions if gravity increases near the core of the planet, seeking clarity on the topic.
  • Another participant asserts that, assuming uniform density, only the mass of the interior contributes to gravitational pull, while the outer shell has no effect.
  • A participant presents a logic argument suggesting that gravity remains constant as one approaches the core due to mutual attraction between the Earth and the individual.
  • Another participant challenges this logic, stating that gravitational pull decreases to zero at the center of the Earth under the assumption of uniform density.
  • A different perspective illustrates that within a spherical shell, gravitational forces cancel out, leading to zero net force at the center.
  • A participant shares a link to a theory of gravity, although it is later noted that the link does not work.
  • One participant requests clearer language to avoid confusion regarding the gravitational effects of surrounding mass.

Areas of Agreement / Disagreement

Participants express disagreement regarding the behavior of gravity as one approaches the Earth's core, with some arguing that gravity remains constant while others contend it decreases to zero.

Contextual Notes

Assumptions about uniform density and the implications of gravitational forces within spherical shells are central to the discussion but remain unresolved.

naler62188
Messages
1
Reaction score
0
Help! Gravity

im not sure if I am in the right place but, i was wondering if gravity increases when you get near the core of the planet. i have done research and have not found anything conclusive. i need help with this topic. any information or thoughts would be apriciated.
 
Physics news on Phys.org
No it does not.
Traveling inwards, and assuming uniform density, only the mass of the interior ball will contribute; the effect from the outer shell is zero.
 
Gravity is the attraction of masses. You are attracted to the Earth and the Earth is attracted to you.

A logic argument:

1. If you were only attracted to the Earth, then only you would fall toward the earth.

2. If the Earth were only attracted to you, then only the Earth would fall toward you.

3. If only one object were attracted (as in 1 or 2), how could it hold it's place in space while it attracted the other object? What would it be holding on to for it to pull the other object to it? Nothing. Therefore, both objects must attract each other. (This is dependent upon their quantity of mass.)

Since you are attracted to the Earth and the Earth is attracted to you, as you get to the core, you are more and more surrounded by an even mass of Earth pulling you with equal force in all directions, while you pull on it in equal directions.

Gravity will be the same, because gravity occurs because of masses which attract each other. The masses are still there (you and the Earth).
 
omin said:
Gravity is the attraction of masses. You are attracted to the Earth and the Earth is attracted to you.

A logic argument:
Sorry, but I can't make any sense out of your "logic" argument. Somehow you have concluded that "gravity will be the same" at the center of the earth. Not true.

Assuming, as arildno stated, a uniform density for the earth, the weight of an object (the net gravitational pull of the Earth on it) will decrease from its usual value at the surface to a value of zero at the center.
 
Picture this in your head: You have a point inside a shell. What's the force on the point due to gravity?

Believe it or not, no matter where you put that point inside the circle, the forces sum to 0.

That means that you can consider every part of the Earth outside of where you are as not affecting you at all, only the stuff further in is.

So when you're in the very middle, everything is in a shell around you... (assuming uniform desnity, etc) 0 force!
 
The link doesn't work :(
 
Since you are attracted to the Earth and the Earth is attracted to you, as you get to the core, you are more and more surrounded by an even mass of Earth pulling you with equal force in all directions, while you pull on it in equal directions.

The effect of the mass "surrounding" you (please be more concise with your language to avoid confusion on the part of students) has no gravitational effect (think spherical symmetry and gauss's law for gravity.)
 

Similar threads

  • · Replies 9 ·
Replies
9
Views
4K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 18 ·
Replies
18
Views
3K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 22 ·
Replies
22
Views
2K
  • · Replies 8 ·
Replies
8
Views
4K
  • · Replies 0 ·
Replies
0
Views
2K
  • · Replies 42 ·
2
Replies
42
Views
8K
  • · Replies 15 ·
Replies
15
Views
7K