Do two masses gravitate to their centre of mass

In summary, if two masses are falling towards each other under gravitational attraction, they will meet at their joint center of mass, whether they are point masses or not. This is due to the fact that the center of mass remains stationary during the in-fall and the masses will meet at the collision point at the same time.
  • #1
jja
2
0
Given two masses falling towards each other under gravitational attraction, do they meet at their joint center of mass, assuming other gravitational forces are negligible?
 
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  • #2
answering own question

On reflection, to a (massless :-) observer at the center of mass of the two in-falling masses, the center of mass must remain stationary during the in-fall (because there is no force to move it), therefore the two masses must meet at the center of mass. This means the time for each mass to reach the collision point must be equal (which may make it easier to calculate the time it takes for them to arrive at the collision point?) Is this correct?
 
  • #3
If you have two point masses, they will meet at their center of mass by construction.

If they are not point masses, they will meet where their surfaces touch.
 

1. What is the center of mass?

The center of mass is the point in an object or system where the mass is evenly distributed in all directions. It is the point around which an object or system will rotate if placed on a pivot.

2. How does the center of mass affect gravitational attraction between two masses?

The center of mass plays a crucial role in determining the gravitational attraction between two masses. The two masses are drawn towards each other because the center of mass of the system is in between them and exerts a force on both of them.

3. Do two masses always gravitate towards their center of mass?

Yes, two masses always gravitate towards their center of mass, regardless of their distance apart. This is due to the fundamental law of universal gravitation which states that all objects with mass are attracted to each other.

4. Is the center of mass always located within the physical boundaries of an object?

No, the center of mass can be located outside the physical boundaries of an object. This is because the center of mass is determined by the distribution of mass within an object, not its physical shape or size.

5. How can the center of mass be calculated?

The center of mass can be calculated by taking the weighted average of the positions of all the individual masses in a system. This can be represented mathematically as:

x_cm = (m1x1 + m2x2 + ... + mnxn) / (m1 + m2 + ... + mn)

y_cm = (m1y1 + m2y2 + ... + mnyn) / (m1 + m2 + ... + mn)

z_cm = (m1z1 + m2z2 + ... + mnzn) / (m1 + m2 + ... + mn)

Where x, y, and z represent the coordinates of each mass, and m represents the mass of each individual object in the system.

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