CHAPTER 7

Question 1

How long does it take light to travel from Neptune to Earth

Answer 1

4 hours

Question 2

What evidence supports the nebular hypothesis

Answer 2

1. rings of material(planets) surrounded the sun,
   a) Explains why planets move in the same direction, in the same plane
   b) disks are observed around other stars
   c) Solar system is flat

Question 3

What are the conditions for gass to colapse

Answer 3

if the outward force is less than gravity, the object contracts, if it is greater objects expands, stable objects are balanced

Question 4

What happens to materials in the disk

Answer 4

1. They could travel inwards towards the falling star at its center
2. remains in disk to form planets and other objects
   3, ejected back into interstellar space

Question 5

What did other scientists try to find

Answer 5

tried to find the history of the solar system,
1. they found that the early solar systems must have been flat and
2all planets moved in the same direction orbiting the sun .
3.larger bodies must have grown from aggregation of smaller bodies

At the end proves that sun was surrounded by a disk of gaseous and solid material, and the sun formed from it.

Question 6

What more did the scientists discover

Answer 6

They discovered that astro and scientists had come to the same picture, concluded that earth had all orbitting bodies came from interstellar cloud that collapsed to form the star

Question 7

How do planets form a disk around young stars

Answer 7

As cloud of interstellar gas collapsed to form a protostar, gravitational energy converted to heat energy and radiation and around the sun was a disk of gas and dust, and materials in disk followed the same laws of motion

Question 8

what causes protoplanetary disks to form

Answer 8

conservation of angular momentum

Question 9

What are three factors that determine angular momentum

Answer 9

1. how fast the object is rotating
   2, mass of object
2. how mass of object is distributed according to spin axis.

Question 10

Explain how both iceskater and interstellar cloud are subject to conservation of angular momentum

Answer 10

We already know that for angular momentum to be conserved, if one quantity changes another quantity has to follow,
FOR SKATER, HER MASS DOES NOT CHANGE, SHE CAN CHANGE RATE OF SPIN BY PULLING OR EXTENDING HER ARMS OR LEGS
PULLS HER ARMS=HER DISTRIBUTION OF MASS CHANGES AND SHE MUST MOVE FASTER TO MAINTAIN SAME ANGULAR MOMENTUM

WHEN ARMS ARE HELD TIGHTLY IN FRONT OF HER AND ONE LEG IS WRAPPED AROUND ANOTHER SHE BECOMES A BLUR, THE CLOUD DID THE SAME IT SPUN FASTER AND FASTER AS IT COLLAPSES.

Question 11

What proves that angular momentum was not conserved during the formation of the sun

Answer 11

Before it collapsed it would have been moving slowly, when it collapsed it would spin very fast, and it spun very fast more than how fast the sun spins today, it continued like that the sun would have turn itself a part

Question 12

Explain how AM is conserved in disk formation

Answer 12

GOING BACK TO SKATER, if the SKATER BENDS HER KNEE COMPRESSING THEMSELVES DOWNWARD SPEED DOES NOT CHANGE,

INTER cloud can move like this flattening itself without changing its speed .

1. As clod collapses self gravity increases and inner parts begin to fall freely inward raining down on the growing object at the center.
2. outer portions lose support of the collapsed inner portion, and they fall inward
3. material makes forward inward plunge into a accretion disk.

Question 13

Where does angular momentum go

Answer 13

As materials fall into the disk, motion perpendicular to disk stops abruptly but motion of mass parallel to surface of the disk adds to disk total angular momentum, as a result AM of infalling materials is transferred to disk

Question 14

What happens to matter on the accretion disk

Answer 14

it either becomes parts of the star or is ejected back into interstellar space in the form of jets, the matter left behind becomes planets

Question 15

How do large objects form

Answer 15

random motions of gas within protoplanetary disks push smaller grains of slid towards larger grains

Question 16

what is the sticking process, when small and larger objects stick.

Answer 16

this is due to same static electricity that causes dust bunnies to grow under the bed.

Question 17

what happens when clumps grow to 100 meters across

Answer 17

objects are so far apart they collide less often,growth rate slows down but does not stop

Question 18

what must clumps do to stick together

Answer 18

They must collide together very gently and must go at 0.1m/s

Question 19

What happens to kilometer sized objects

Answer 19

kilometer sized objects are massive enough that it pulls on nearby bodies

Question 20

Formation of planets

Answer 20

These planetismals combine with one another to form planets.

Question 21

Explain the nature of inner planets and outer planets

Answer 21

inner= small and mostly rocky
outer= large and gaseous

Question 22

Explanation of conservation of energy

Answer 22

Energy is never lost but stored and converted in this order G.P.E, Kinetic energy then to thermal energy

Energy

Question 23

What is the inner and outer disk made of

Answer 23

inner disk is made of refractory materials , outer disk are water, ice materials, reflects in planets,

inner planets are rocky, outer planets= ice

Question 24

An example of planet migration

Answer 24

Uranus and Neptune may have been closer to Jupiter and Saturn but moved outwards by gravitational encounters with with Jupiter and Saturn

Also when a planet gives up some of its orbital angular momentum to the disk material around it

Question 25

How does the massive planet grow

Answer 25

Once a planet is formed it takes whaterver gas it can f
more massive young planets because of theor gravitational pull can take most of the hydrogen and helium gas. then gas from a mini accretion disk moves and falls onto a planet

Question 26

How do a group of moons orbit a planet

Answer 26

some of material in mini accretion disk might stay behind to coalesce into larger bodies making a mini solar system = a group of moons that orbit the sun

Question 27

How do small planets go

Answer 27

Because they are small they do not have enough gravitational pull to hold on to the gas hydrogen and helium, it may hold but not long enough. Since the temperatures are high in inner planets atoms in hydrogen and helium are moving faster hence they escape

Question 28

Example of the second atmosphere

Answer 28

is formed later in life of a planet. E.G

Volcanism realeases heavier and slower moving gas, such as Carbondioxide and water vapor

Comets formed in outer part of disk fall inwads towards the new star long after the planet is formed

Question 29

How did terrestial planets form

Answer 29

within 5AU of the disk, rocks, metal and planetismals quickly grew larger to become the dominant masses in their orbits