Physics H - Universal Gravitation

The Universe, Magnets, Black Holes

How long ago did the Big Bang occur?

almost 14 billion years ago

Is the Big Bang an explosion?

NO

What is the Big Bang?

rapid expansion of time and space

Is the universe expanding?

Yes, it is constantly expanding faster and faster

What is Hubble’s law?

The farther away a galaxy is, the faster it is moving away

cosmis background radiation

radiation leftover from the big bang

What do scientists think our solar system formed from?

a solar nebula

What is a solar nebula?

a giant, rotating cloud of gas and dust

How was the sun formed?

The nebula collapsed due to gravity and spun faster and faster until it was flattened into a disk. The material was pulled towards the center to form the sun.

When was the sun formed?

about 4.6 billion years ago

Planetismal

the asteriod-like bodies that formed the building blocks of planets

How did the planets form?

The planetesimals collided and grew larger by sticking together, eventually combining to make the planets

dark energy

a force that is causing the expansion of the universe to accelerate

dark matter

matter that does not give off electromagnetic radiation

How can scientists infer approximately how long the universe has been expanding?

they know the rate of expansion

What are two possibilities of what will happen to the universe in the future?

1. the universe will continue to expand

2. the force of gravity will pull everything back in, reverse big bang, crushed into a giant black hole

magnetism

refers to the properties and interactions of magnets

magnet

a device which carries a static magnetic field around it

magnetic field

a field present around a magnet which exerts a force on other magnetic materials

magnetic field lines

Imaginary lines that represent the strength and direction of a magnetic field, denser where the field is stronger (closer they are the stronger the force)

magnetic pole

the south and north end of a magnet

Where do magnetic field lines start and end?

start at north pole and end at the south pole

opposite poles attract and same poles repel

Geographical and magnetic poles of Earth.

temporary magnet

a metal that performs like a magnet in the presence of a magnetic field but loses magnetism when not in one

permanent magnets

placing materials into a very strong magnetic field

What are the few minerals that exhibit magnetic properties?

nickel, iron, cobalt, some of their alloys, and a few rare earth metals

What does an MRI (magnetic image resonance) do?

It uses magnetism and radio waves to map the inside of a person’s body

What is a black hole?

`an object so massive nothing can escape from it - not even light

How is a black hole formed?

when the center of a very massive star collapses in upon itself

Who was first person to suggest the existence of a black hole?

Karl Schwarschild

Who named them black holes?

John Wheeler

What is escape velocity of a black hole?

the object must be moving away from the black hole faster than a certain threshold - speed of light

What is the escape velocity of Earth?

2500 mph

What is the escape of a black hole?

speed of light - 671,080,888 mph

Why is the gravity of a black hole so strong?

a massive amount of matter is concentrated into a tiny space