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Astronomers using the Hubble Space Telescope deduced the presence of an extremely massive core in the distant galaxy M87, so dense that it could be a black hole (from which no light escapes). They did this by measuring the speed of gas clouds orbiting the core to be $780 \mathrm{~km} / \mathrm{s}$ at a distance of 60 light-years $\left(5.7 \times 10^{17} \mathrm{~m}\right)$ from the core. Deduce the mass of the core, and compare it to the mass of our Sun.

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$5.2 \times 10^{39} \mathrm{kg}$$2.6 \times 10^{9}$ solar masses

Physics 101 Mechanics

Chapter 6

Gravitation and Newton's Synthesis

Physics Basics

Newton's Laws of Motion

Applying Newton's Laws

Gravitation

Cornell University

Hope College

University of Winnipeg

McMaster University

Lectures

03:43

In physics, dynamics is the branch of physics concerned with the study of forces and their effect on matter, commonly in the context of motion. In everyday usage, "dynamics" usually refers to a set of laws that describe the motion of bodies under the action of a system of forces. The motion of a body is described by its position and its velocity as the time value varies. The science of dynamics can be subdivided into, Dynamics of a rigid body, which deals with the motion of a rigid body in the frame of reference where it is considered to be a rigid body. Dynamics of a continuum, which deals with the motion of a continuous system, in the frame of reference where the system is considered to be a continuum.

03:55

In physics, orbital motion is the motion of an object around another object, which is often a star or planet. Orbital motion is affected by the gravity of the central object, as well as by the resistance of deep space (which is negligible at the distances of most orbits in the Solar System).

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Astronomers using the Hubb…

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The best evidence for a bl…

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Astronomical observations …

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Astronomers have observed …

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At the Galaxy's Core.…

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So here we want to find the mass of the galaxy as well as how many solar masses are in the galaxy. We know that the velocity is going to be equal to velocity of the object. In orbit will be the gravitational, constant times the mass of the body that it's orbiting around. Divided by our man, we find that the mass of the galaxy will be equal to R V squared over G. And so we confined the mass of the galaxy. This is going to be equal, Tio 5.7 times 10 to the 17th meters times 7.8 times 10 to the third meters per second quantity squared and then divided by the gravitational constant 6.67 times 10 to the negative 11th. And we find that the mass of the galaxy is going to be 5.2 times 10 to the 39th kilograms. And so the number the number of solar masses we'd be equal to the mass of the galaxy divided by the mass of our sun, knowing that we have the knowing the mass, the mass of our own son. So this would be 5.2 times 10 to the 39th kilograms and then this would be divided by two times 10 to the 30th kilograms. And this is giving us 2.6 times 10 to the ninth Solar masses. So this is the second part. And this would be, of course, the mass of the galaxy. That is the end of the solution. Thank you for watching.

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