Angular Velocity for Constant Separation Distance

In summary, the required angular velocity $\omega$ for maintaining a constant separation distance $r_0$ between two equal masses orbiting each other in space can be found by balancing the potential energy due to gravity and the rotational kinetic energy. This can be expressed through the force of gravity and centripetal acceleration equations, with the tangential velocity being equal to $\omega \,r_0$. The position vector for the center of gravity does not affect the calculation, as it can be chosen at any point between the two bodies.
  • #1
Dustinsfl
2,281
5
Determine the required angular velocity $\omega$ of the relative position vector in order to maintain a constant separation distance $r_0$ for two equal masses.

What equations are needed for this?
 
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  • #2
To me it seems as if you have to balance the potential energy due to gravity against the rotational kinetic energy. That is, it seems as if you're in outer space with two equal masses, and they are rotating around each other like a binary star system. If the distance between them is constant, how fast are they rotating around each other?
 
  • #3
Ackbach said:
To me it seems as if you have to balance the potential energy due to gravity against the rotational kinetic energy. That is, it seems as if you're in outer space with two equal masses, and they are rotating around each other like a binary star system. If the distance between them is constant, how fast are they rotating around each other?

Fast enough to not be pulled in by the others gravity and a slow enough that they don't fly off.
 
  • #4
dwsmith said:
Fast enough to not be pulled in by the others gravity and a slow enough that they don't fly off.

Exactly. So I think you'd have the force due to gravity being

$$|F_{g}|=\frac{m^{2}G}{r_{0}^{2}},$$

and the centripetal acceleration being

$$a_{c}=\frac{v_{\tan}^{2}}{r_{0}}=\frac{F_{c}}{m}.$$

Also note that $v_{\tan}=\omega \,r_{0}$.
 
  • #5
Is this question talking about the position vector for the center of gravity of the two bodies?

If we set the origin to be the center of gravity, the bodies orbit it in a uniform circle with radius 1/2r_0.
I can just find the angular velocity on this circle?
 
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  • #6
dwsmith said:
Is this question talking about the position vector for the center of gravity of the two bodies?

If we set the origin to be the center of gravity, the bodies orbit it in a uniform circle with radius 1/2r_0.
I can just find the angular velocity on this circle?

It shouldn't matter. You could choose your frame of reference to be at the center of one of the bodies just as well.
 

FAQ: Angular Velocity for Constant Separation Distance

What is a relative position vector?

A relative position vector is a mathematical representation of the position of an object relative to a reference point. It is used to describe the location of an object in a specific coordinate system.

How is a relative position vector different from a displacement vector?

While both relative position and displacement vectors describe the location of an object, they differ in that displacement vectors only consider the change in position from one point to another, while relative position vectors take into account the position of the object relative to a reference point at a specific moment in time.

What information does a relative position vector include?

A relative position vector includes both magnitude and direction. The magnitude is the distance from the reference point to the object, while the direction is the angle at which the object is located from the reference point.

How is a relative position vector represented?

A relative position vector is typically represented by an arrow pointing from the reference point to the object. It can also be represented by its components in the x, y, and z directions.

How is a relative position vector calculated?

A relative position vector can be calculated using the Pythagorean theorem and trigonometric functions. The magnitude can be found by taking the square root of the sum of the squares of the x, y, and z components, and the direction can be determined using trigonometric ratios.

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