Is the Moon's Gravity Calculation Correct?

  • Context: Undergrad 
  • Thread starter Thread starter Oops
  • Start date Start date
  • Tags Tags
    Moon Radius
Click For Summary

Discussion Overview

The discussion revolves around the calculation of the Moon's gravitational acceleration and its comparison to Earth's gravity. Participants explore the correctness of the mathematical approach and the underlying physics concepts, including gravitational forces and ratios of acceleration.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant questions the correctness of the calculus used to calculate the Moon's gravity, specifically regarding the conversion of decimal points.
  • Another participant suggests that the calculation is intended to demonstrate why the Moon's gravity is approximately 1/6 of Earth's gravity.
  • A different participant critiques the arithmetic and physics of the original calculation, indicating potential errors.
  • One participant mentions the need for a higher order derivative if the goal is to calculate tidal forces, implying a more complex approach may be necessary.
  • Another participant expresses confusion about the term "higher order derivative" and seeks clarification.
  • One participant affirms that the calculation of acceleration due to gravity on the Moon and its comparison to Earth appears correct, although they express uncertainty about their own knowledge.
  • A later reply provides links to search results for gravitational calculations, suggesting alternative methods or confirmations of the ratios involved.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the correctness of the original calculation. There are multiple competing views regarding the approach and the interpretation of the results, with some expressing doubts about the arithmetic and physics involved.

Contextual Notes

Some participants highlight potential limitations in the original calculation, including arithmetic errors and the appropriateness of the methods used for the intended purpose. The discussion does not resolve these issues.

Oops
Messages
11
Reaction score
0
Is this calculus correct, or do the decimals points have to be converted ?
Thanks so much , cause I'm stuck


The gravitational constant is 6.673 * 10 to the -11th power.
The radius of the moon is 1737400 meters.
Its mass (which is independent of gravity) is 7.35 * 10 to the 22nd power kg.
Now, given that F=ma and F=GmM/r squared, we can set
a = GM/r squared.
So:
a = (6.67300f * (Math.Pow(10, -11)) * 7.36f * Math.Pow(10, 22))/(1737400f*1737400f)
Running this I get a = 1.62704402190015.
Now, since F (the force of gravity) = ma, then for the same object, F1/F2 = ma1/ma2. This means that the ratio of the forces is equal to the ratio of accelerations since the m cancels out: F1/F2 = a1/a2.
Finally, we take acceleration on the earth, which is roughly 9.8m/s/s. Dividing our calculated value for a by that, we get:
1.62704402190015 / 9.8 = 6.02319
And there it is, our 1:6 ratio.
 
Astronomy news on Phys.org
Please does anyone have an answer for me. I just read this in another forum,but I don't know if its correct or not.
 
Looks like this person has some trouble with both arithmetic and physics.

- Warren
 
Chroot, thank you so much for answering - I really appreciate it
could you tell me what's wrong with this calculus ?
It's troubling me a lot

Thnak you - I'm kind of getting desperate :(
 
Oh, it suppose to determine why the gravity of the moon is 1/6 of the earth's
 
It appears you are trying to calculate tidal forces. In that case, you need to use a higher order derivative.
 
Hi Chronos
Thanks for answering
What do you mean ? What's meant by a higher order derivative ?
 
It looks like you're just calculating what the acceleration due to gravity is on the surface of the Moon and then comparing it to the on the surface of the Earth. Looks good to me, but what do I know.
 
  • #10
Now I get it. thanks you guys
 

Similar threads

High School Earth & Moon Gravity Gradient: Investigating Its Impact
  • · Replies 33 ·
2
Replies
33
Views
6K
Undergrad How Does the Balloon Analogy Explain the Expansion of the Universe?
  • · Replies 5 ·
Replies
5
Views
3K
Undergrad Comparison of tidal forces acting on the Moon vs Enceladus
  • · Replies 56 ·
2
Replies
56
Views
7K
Undergrad Calculation the orbital period of Moon.
  • · Replies 2 ·
Replies
2
Views
3K
Graduate Attraction Forces During Total Eclipse: Sun, Moon, and Earth Explained
  • · Replies 4 ·
Replies
4
Views
3K
The force LRO experiences due to moons gravity?
  • · Replies 3 ·
Replies
3
Views
2K
Acceleration on the Moon: How Does Gravity Affect Objects?
  • · Replies 3 ·
Replies
3
Views
2K
Undergrad Equation of Gravity's influence relative to objects
  • · Replies 1 ·
Replies
1
Views
2K
Universal Gravitation and/or Tidal Force
  • · Replies 1 ·
Replies
1
Views
2K
Graduate A Puzzle Involving the Moon's Orbital Motion
  • · Replies 19 ·
Replies
19
Views
2K