Calculating Planet Mass from Stellar and Orbital Speed

In summary, to calculate the mass of a planet, the formula M = v²r/G is used, which takes into account the orbital speed, distance from the star, and gravitational constant. The star's mass is crucial in this calculation as it affects the strength of the gravitational force. However, this method is only applicable for planets with a single star and may not always provide an accurate measurement due to various factors. Other methods such as radial velocity measurements and transit photometry can also be used to calculate a planet's mass, each with their own limitations and strengths.
  • #1
Dustin salinas
5
0

Homework Statement



Stellar mass 3.8 x 10^30 kg
Star's orbital speed: 90 m/s
Planet's orbital speed: 95,000 m/s

Whats the mass of the planet in kilograms
[/B]

Homework Equations

The Attempt at a Solution

 
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  • #2
You seem to have forgotten to fill in "Relevant equations" and "The attempt at a solution"!
 
  • #3
This is my sons homework I am just trying to get the answer and see if someone can show me how to get it so i can help him
 
  • #4
Dustin salinas said:

Homework Statement



Stellar mass 3.8 x 10^30 kg
Star's orbital speed: 90 m/s
Planet's orbital speed: 95,000 m/s

Whats the mass of the planet in kilograms
[/B]

Homework Equations

The Attempt at a Solution

Can you find the distance to the centre of rotation from each body? What does that tell you about relative mass?

AM
 
  • #5
No that's all the information he's given
 
  • #6
Dustin salinas said:
This is my sons homework I am just trying to get the answer and see if someone can show me how to get it so i can help him

We don't give out answers to homework questions, so that's why you're being asked to find the center of rotation. It's the same point as the center of mass.

We could teach you how to make the right answer, but instead we teach you how to make sense of the physics involved in making the answer. If you communicate the former to your son and not the latter it won't have any instructional value.
 
  • #7
O ok apparently i came to the wrong forum. I thought i could just get help to teach him how to make the right answer. Like the formula to finding mass with those factors
 
  • #8
I suggest that your son join Physics Forums.
 
  • #9
Apparently him joining wouldn't get him closer to an answer
 
  • #10
Thread closed.
Dustin salinas said:
Apparently him joining wouldn't get him closer to an answer
As already mentioned, we aren't a service where someone posts a question and we give the answer. If your son wants help, he should become a member, and we will steer him in the right direction, but he has to show some effort.
 

1. How do we calculate the mass of a planet?

To calculate the mass of a planet, we use the formula M = v²r/G, where M represents the mass of the planet, v represents the orbital speed of the planet, r represents the distance between the planet and its star, and G represents the gravitational constant. This formula is derived from Kepler's Third Law of Planetary Motion and is known as the "mass function".

2. What is the role of the star's mass in calculating the planet's mass?

The star's mass plays a crucial role in calculating the planet's mass as it determines the strength of the gravitational force between the star and the planet. This force affects the orbital speed of the planet, which is a key component in the mass function formula.

3. Can we use this method to calculate the mass of all planets?

No, this method is only applicable for planets that have a single star as their source of gravity. It cannot be used to calculate the mass of planets in binary or multiple star systems.

4. How accurate is this method in determining the mass of a planet?

This method can provide a good estimate of a planet's mass, but it is not always accurate due to various factors such as the uncertainty in the distance between the planet and its star, and the possibility of other objects affecting the orbital speed.

5. Are there any other methods for calculating a planet's mass?

Yes, there are other methods such as radial velocity measurements, transit photometry, and astrometry that can be used to calculate a planet's mass. Each method has its own limitations and strengths, and scientists often use a combination of these methods to get a more accurate measurement.

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