Download ANSWER KEY to Black Hole Discussion Questions We could not

ANSWER KEY to Black Hole Discussion Questions
1. We could not compress the aluminum foil-covered balloon when it was inflated because the air inside
the balloon was resisting the pressure we exerted upon it. Our pressure simulated gravity pulling the
matter in the star toward its center and the air within the balloon simulated the outward flowing
energy from thermonuclear fusion. These two factors balance each other out, so the star stays at
equilibrium.
2. If a real star were the size of the balloon, then the black hole would be much, much tinier than our
model black hole. A real black hole that has formed from a massive star is smaller than the tip of a
pencil!
3. Building the star with more layers of gas (represented by the foil) would make the star more massive. It
would also result in the formation of a more massive black hole, since there would be more material
with which to form the black hole.
4. Although they have a different size, since they are made from the exact same amount of material, the
model star and the model black hole have the same mass. However, since the model black hole is
smaller, it has more material contained in less volume, and therefore has a higher density than the
model star. This would also be true for a real black hole, which would be even smaller and much, much
denser.
5. Black holes do not suck up nearby material. If the Sun were magically converted into a black hole,
Earth's orbit would not change! Earth would continue to “fall around” the black hole, but not fall
into it. However, life on Earth would cease to exist, seeing as it is dependent on the sun’s light and
heat, which would no longer be emitted.
More detail: Material generally falls into a black hole when it collides with other material orbiting
the black hole. The collision alters the material's orbit. Instead of orbiting a comfortable distance
from the black hole, the material is now orbiting too close to the black hole – within the boundary
of its event horizon. Then the black hole's enormous gravity traps the material in a one-way spiral
to oblivion.
Reminder: Our sun is not massive enough to become a black hole!