S3W5 FC The life Cycle of Stars

Consider a hydrogen molecule alone out in the middle of space. How would you describe the forces on that molecule?

Consider that same molecule out in the middle of space on the edge of a large cloud of loose hydrogen atoms. How would you describe the forces on that molecule?

Read Chapter 13.1-13.4. Do you have any questions?

Define an interstellar cloud.

It is estimated that an interstellar cloud around 50 parsecs wide eventually became our sun and planets. If there are 3.2 light years to a parsec, how many light years wide was that interstellar cloud?

explain what a light year is

Watch this quick video on why the solar system is flat.

You know how a ton of equations depend on mass? like F=ma? when we talk about rotation, we don't talk about mass, we talk about moment of inertia. it's basically mass that depends a bit on how big the radius of a thing is, because when something is rotating, its rotating around something, and the radius from that something matters. think about a bolt that you are trying to loosen. If you twist it with your fingers, and then try to twist it with a wrench, which one is easier to use?

is the radius between the center of your bolt bigger or smaller than the radius between your hand on the wrench and the bolt?

does where you put your hand along the wrench matter?

Think about when a figure skater starts spinning. What happens as the figure skater brings in her arms?

The moment of inertia of a sphere is the 2/5mr^2, where m is the mass, and r is the radius. If you calculate the moment of inertia of all the particles of a nebula when it has a radius of 50 light years, and then calculate it again when the the radius is 10 light years, the moment of inertia has

Angular momentum is always conserved. When the skater decreases her radius (brings her arms in) she decreases her moment of inertia, but her angular momentum stays the same. Angular momentum is moment of inertia x angular velocity. If you decrease the moment of inertia and the angular moment stays the same, what happens to the skaters velocity?

A nebula is 2x10^30 kg in mass, and has a radius of 50 light years. using the equation 2/5mr^2, calculate the moment of inertia of of the nebula

A nebula is 2x10^30 kg in mass, and has a radius of 1 light years. using the equation 2/5mr^2, calculate the moment of inertia of of the nebula

Thinking about this, how much faster do you think the angular velocity of the nebula is when it shrinks from 50 light year radius to a 1 light year radius?

What did he mean by that bit about "if the universe were four dimensions"

lets go back to the book. would you expect more nuclear fusion or less nuclear fusion when the sun is running out of hydrogen?

What is the force that kept the star's gravity from making it collapse?

Using the last two questions, explain why the star core would shrink as it runs out of fuel.

define bipolar flow

Explain how things change in the death of a star when the star is much bigger than our sun