Universal Gravitation and X-ray pulses

In summary, the conversation discusses using Kepler's laws to calculate the orbit radius of a blob of ionized matter around a black hole, based on X-ray pulses recorded during rocket flights. The equation used is T^2 = (4pi^2r^3)/(GM), and the resulting answer is 110 km. The conversation also mentions the possibility of Kepler's laws not applying when dealing with black holes and the need for further consideration.
  • #1
Antepolleo
40
0
I'm having a little bit of a problem with this one. Here's the question:

X-ray pulses from Cygnus X-1, a celestial x-ray source, have been recorded during high-altitude rocket flights. The signals can be interpreted as originating when a blob of ionized matter orbits a black hole with a period of 4.7 ms. If the blob were in a circular orbit about a black hole whose mass is 18 * MSun, what is the orbit radius?


Here's my train of thought. I used one of Kepler's laws:

[tex]
\begin{equation*}
\begin{split}
T^2 = \frac{4\pi^2r^3}{GM_{blackhole}}\\
r = (\frac{T^2GM_{blackhole}}{4\pi^2})^(\frac{1}{3})\\
\end{split}
\end{equation*}
[/tex]

I changed the milliseconds to seconds, and I got a answer of 110196.285 meters. I'm letting the mass of the sun be 1.991 x 1030 kg.

I enter this into webassign, but I doesn't like it. What am I doing wrong?
 
Physics news on Phys.org
  • #2
I don't see anything wrong in what you did (other than keeping too many significant digits). Try rounding the answer to 110 km.
 
  • #3
Kepler's laws won't apply when you're this close to a black hole. I'll have to think about this one a bit. Although the title of this thread suggests you're supposed to be using Newtonian mechanics...

- Warren
 
  • #4
These questions were in the "Universal Gravitation" chapter. It's got to have something to do with either Kepler's laws, or the law of universal gravitation.
 
  • #5
Originally posted by gnome
I don't see anything wrong in what you did (other than keeping too many significant digits). Try rounding the answer to 110 km.

Heh, it was a decimial problem. Thanks for pointing that out.

If only all of these problems would be so simple!
 

1. What is universal gravitation?

Universal gravitation is a scientific principle that explains the force of attraction between any two objects with mass. This force is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.

2. How does universal gravitation relate to X-ray pulses?

X-ray pulses are produced by rapidly rotating neutron stars, also known as pulsars. These pulsars have extremely strong gravitational fields, which can affect the path of X-ray radiation and cause it to pulse periodically.

3. What is the significance of X-ray pulses in understanding universal gravitation?

Studying X-ray pulses from pulsars can provide valuable insights into the nature of gravity and its effects on massive objects. By observing the changes in the pulsar's pulse period over time, scientists can test and refine theories of universal gravitation.

4. How do scientists detect and measure X-ray pulses?

Scientists use X-ray telescopes to detect and measure X-ray pulses from pulsars. These telescopes are designed to collect and focus X-ray radiation from space, allowing scientists to study the intensity and timing of the pulses.

5. Are there any current research projects or experiments related to universal gravitation and X-ray pulses?

Yes, there are several ongoing projects and experiments that are focused on studying universal gravitation and X-ray pulses. These include the NICER (Neutron star Interior Composition Explorer) mission, the XMM-Newton space telescope, and the Advanced LIGO (Laser Interferometer Gravitational-wave Observatory) experiment.

Similar threads

  • Special and General Relativity
2
Replies
43
Views
4K
  • Classical Physics
Replies
9
Views
936
  • Introductory Physics Homework Help
Replies
1
Views
2K
  • Introductory Physics Homework Help
Replies
3
Views
4K
Replies
1
Views
1K
  • Astronomy and Astrophysics
Replies
1
Views
2K
  • Special and General Relativity
Replies
8
Views
2K
  • Special and General Relativity
Replies
16
Views
2K
  • Introductory Physics Homework Help
Replies
2
Views
1K
Back
Top