HOW BIG IS A BLACK HOLE

BY THE END OF THE SESSION YOU SHOULD BE ABLE TO:

Explain what the Schwarzchild radius is.

Recall which principles in physics are needed to derive it.

Derive the equation for the Schwarzchild radius with some help.

WHAT DO YOU KNOW ABOUT BLACK HOLES ALREADY?

ARTISTS IMPRESSIONS OF BLACK HOLES

WHAT PRINCIPLES IN PHYSICS MIGHT WE USE TO DETERMINE THE SIZE IF A BLACK HOLE?

We want to find out the radius of the event horizon.

ESCAPE VELOCITY OF A ROCKET LEAVING EARTH

We will compare the energy the rocket has to the energy it needs to completely ‘escape’ from the earth.

ENERGY REQUIRED TO ESCAPE FROM EARTH

Gravitational constant

Mass of the Earth

Mass of the Rocket

Distance of rocket from centre of mass of The Earth

Gravitational potential

Work done to move an object of mass (m) through a Gravitational Potential (V)

ENERGY REQUIRED TO ESCAPE FROM EARTH

CALCULATING ESCAPE VELOCITY

Use the law of conservation of energy

WHAT ABOUT ESCAPING FROM A BLACK HOLE?

What is the fastest thing that cannot escape from a black hole?Now let M be the Mass of the black hole

THE SCHWARZCHILD RADIUS

BY THE END OF THE SESSION YOU SHOULD BE ABLE TO:

Understand what the Schwarzchild radius is.

Recall which principles in physics are needed to derive it.

Derive the equation for the Schwarzchild radius with some help.