An object which experiences two gravitational force

In summary, the conversation discussed the problem of calculating the path of a Voyager 5 with two Earths, known as Euler's three-body problem, and its analytical solution requiring calculus. The idea of calculating the motion in small steps and using a spreadsheet or programming language was suggested. It was also mentioned that learning calculus from a book can be difficult, but there is a somewhat nice solution for this particular problem.
  • #1
adjacent
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Homework Statement


attachment.php?attachmentid=68888&stc=1&d=1398073020.png

Let there be a Voyager 5 with two Earth's(I mean they have the same mass and density etc)
At start,Voyager 5 will be stationary.
I want to calculate the path of the Voyager and if possible,draw it on a graph.

Homework Equations


##F=\frac{GMm}{r^2}##


The Attempt at a Solution


I know I have to find the resultant force and accelerate the voyager in that direction.
My problem is that if I move it a little bit,the forces will change both direction and magnitude.Then I will again have to find the resultant force and accelerate it.This would be boring.
Is this really that difficult?Is there any other way?
I need your help here. :smile:
 

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  • #2
This is known as Euler's three-body problem, and its analytical solution requires calculus. If I remember correctly, you are not there yet.

You could try solving this numerically, using a spreadsheet or some programming language, if you know one.
 
  • #3
voko said:
This is known as Euler's three-body problem, and its analytical solution requires calculus. If I remember correctly, you are not there yet.

You could try solving this numerically, using a spreadsheet or some programming language, if you know one.
:cry:
I don't know any programming languages.How can I use a spreadsheet to solve this?

P.S can you recommend a calculus book that will teach it from scratch?
 
  • #4
voko said:
This is known as Euler's three-body problem, and its analytical solution requires calculus. If I remember correctly, you are not there yet.
Even the two-body problem needs calculus to find a solution. The three-body problem has no "nice" solution for the general case.

@adjacent: The idea is to calculate the motion in small steps. For each step, calculate the acceleration, adjust the velocity a bit accordingly, adjust the position a bit accordingly. The quality of the trajectory depends on the step size and the order and formula of those adjustment steps, but to get an idea how it works that does not matter.
 
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  • #5
In a spreadsheet, you would arrange rows of cells, where each row has two cells for position, two cells for velocity, two cells for acceleration, all at some instant of time. The acceleration in each row is computed using the force formula for the position in the row. The position in each row is computed from the position in the previous row plus the velocity in the previous row times the time step between rows. The velocity in each row is computed from the velocity in the previous row plus the acceleration in the previous row times the time step between rows. You need to set up just the first two rows in that way, then using the spreadsheet auto-complete feature (select cells and drag them down) to obtain more rows.

As for learning calculus from a book, it can be done, but is much harder than learning it from a teacher. I would not recommend doing that.
 
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  • #6
mfb said:
Even the two-body problem needs calculus to find a solution. The three-body problem has no "nice" solution for the general case.

In this particular case, there is a (somewhat) nice solution.
 
  • #7
Thanks everyone.I will try to use Microsoft Excel.
 

1. What is a gravitational force?

A gravitational force is the force of attraction between two objects with mass. It is one of the four fundamental forces in nature and is responsible for the motion of planets, stars, and other celestial bodies.

2. How does an object experience two gravitational forces?

An object can experience two gravitational forces if it is located between two massive objects or if it is subjected to the gravitational pull of multiple objects.

3. How do the two gravitational forces affect the object?

The two gravitational forces will pull on the object in different directions, causing it to accelerate in a specific path. The net force on the object is the combination of the two gravitational forces, and it will move in the direction of the stronger force.

4. How can we calculate the magnitude of the two gravitational forces?

The magnitude of the two gravitational forces can be calculated using Newton's Law of Universal Gravitation, which states that the force between two objects is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.

5. Can the two gravitational forces cancel each other out?

Yes, it is possible for the two gravitational forces to cancel each other out if the two forces are equal in magnitude but opposite in direction. This can occur if the object is located at a specific point where the gravitational forces from two massive objects are equal.

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