Centripetal forces and gravity

Click For Summary
SUMMARY

The discussion centers on the relationship between centripetal forces and gravity in the context of frame-dragging near a rotating black hole (BH) with a spin parameter of 0.95. It establishes that the centripetal acceleration can be calculated using the formula v^2/r, where v is the velocity at the photon sphere. The calculated centripetal acceleration is approximately 2.2123e11 m/s^2, and the required velocity to maintain a stable orbit is determined to be 224,290,519 m/s (0.748c). The conversation also explores whether frame-dragging's angular velocity should be included in these calculations and the perception of centrifugal forces within a rotating frame.

PREREQUISITES
  • Understanding of general relativity and black hole physics
  • Familiarity with centripetal acceleration and gravitational forces
  • Knowledge of frame-dragging effects in rotating black holes
  • Basic proficiency in mathematical physics, particularly in using formulas for velocity and acceleration
NEXT STEPS
  • Research the effects of frame-dragging in Kerr black holes
  • Study the mathematical derivation of centripetal acceleration in non-inertial frames
  • Explore the implications of angular momentum in rotating black holes
  • Investigate the concept of centrifugal force in rotating reference frames
USEFUL FOR

Astronomers, physicists, and students of astrophysics interested in the dynamics of rotating black holes and the effects of frame-dragging on orbital mechanics.

stevebd1
Science Advisor
Insights Author
Messages
747
Reaction score
41
On a couple of occasions I've seen it stated that centripetal forces cancel out gravity where centripetal force is v^2/r (expressed in m/s^2 as with gravity). Based on this, if the angular velocity of frame-dragging near a 3 sol BH (spin parameter a = 0.95) was 54,226,630 m/s (0.181c) at the photon sphere (r = 13,291.65 m) and the gravity was ~4.006e12 m/s^2, would the velocity of the frame-dragging be included when calculating the centripetal acceleration required to maintain a stable orbit?

frame-dragging centripetal acceleration= v^2/r = 2.2123e11 m/s^2

in order to maintain a stable orbit, velocity required of an object within rotating frame might be expressed as-

v=\sqrt{(a_{g} -a_{c}) r}

v = velocity required to maintain stable orbit, a_{g} = gravity acceleration, a_{c} = centripetal acceleration, r = radius

in this case, 224,290,519 m/s (0.748c)

Is it considered acceptable to include the frame-dragging's angular velocity when calculating the velocity required to retain a stable orbit at a specific radius around a rotating BH?

Also, if you were rotating within the frame-dragging without any input (i.e. rotating the black hole as a static object within the rotating frame) and you had some form of propulsion directed towards the black hole that counteracted the gravity, would you be aware of centrifugal forces induced by the rotating frame or is the fact that the frame itself is rotating and technically not you mean that no centrifuge would be perceived?

Steve
 
Last edited:
Astronomy news on Phys.org

Similar threads

  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
Replies
12
Views
2K
  • · Replies 22 ·
Replies
22
Views
3K
  • · Replies 86 ·
3
Replies
86
Views
8K
  • · Replies 11 ·
Replies
11
Views
2K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 1 ·
Replies
1
Views
6K
  • · Replies 8 ·
Replies
8
Views
3K
  • · Replies 16 ·
Replies
16
Views
2K