Exam 1 (week 1-7)

Question 1

Why does the moon go through phases?

Answer 1

sunlight ; because the moon orbits around earth and earth orbits the sun

Question 2

Where the moon can be seen at various times for phases

Answer 2

Check picture on iPad

Question 3

How does the moons period of rotation compare with the period of revolution? How does this change your view of the moon?

Answer 3

The moon has a synchronous rotation: the moons rotation = the moons revolution. Since we always see the same side of the Moon

• if the moon did not rotate we would see all sides of a moon

Question 4

What circumstances produce a toll total solar eclipse? What phase is the moon in and where would someone need to be to see the eclipse?

Answer 4

Happens when the moon shadow is cast upon earth
- Can only occur during the new moon
- Need to be in the moon’s shadow to see the eclipse

Question 5

What circumstances produce a total lunar eclipse? What phase is the moon in and where would someone need to be to see the eclipse?

Answer 5

Happens when the moon passes through earths shadow
- Can only occur during a full moon
- seen where sunlight is blocked but orange glow of sunrise and sunset are cast onto the moon

Question 6

Why aren’t there eclipses every month? Where does the moon have to be in the sky to give us an eclipse?

Answer 6

Most months the moon is above or below the plane of our orbit so the shadows miss and eclipses don’t happen
-  happens when the moon is new or full and when it’s on the ecliptic

Question 7

Which type of eclipse are you more likely to see?

Answer 7

Lunar eclipse are most common because earth has a larger shadow and half of earth can see the eclipse at once

Question 8

What is a annular eclipse? Why do they happen?

Answer 8

An annular solar eclipse happens when the moon covers the sun center leaving suns visible outer edges to form a “ring of fire”
- when sun and moon have nearly the same angular diameter in the sky

Question 9

What is retrograde motion?

Answer 9

Apparent motion of a planet in the direction opposite to that of other bodies within its system (planet seems to reverse its direction in sky)

Question 10

What are the main features of geocentric model? Who first suggested it.

Answer 10

• Earth is at the center of the universe and motionless
• All celestial bodies revolve around earth
• Call me observe the motion is the result of the motions Celestial bodies within celestial sphere 
• All celestial bodies are perfect, unchanging, and move in perfectly circular path

Ptolemy suggested it

Question 11

What did the Ptolemy put into his model to try to explain retrograde?

Answer 11

Added epicycles to the geocentric system to try to explain retrograde motion

Question 12

What is the main feature of the heliocentric model? Who advanced this idea?

Answer 12

The sun is the center of the solar system in the universe.
- Copernicus advanced the idea (put the planets in the correct places)

Question 13

How does the Copernican model explain retrograde (Why does retrograde motion really happen)?

Answer 13

In the heliocentric model retrograde motion happens when earth passes an outer planet

Question 14

What was Tycho’s most important contribution in astronomy?

Answer 14

Please instead he’s a new star; Read very accurate observations on positions of stars and planets in the
- To prove comments weren’t in the atmosphere

Question 15

What are keplers 3 laws of planetary motion?

Answer 15

1. The orbit of a planet about the sun is on ellipse (oval) with the sun at one focus
2. Play planet moves faster so that’s all of it when it is closest to the sun moves lowest in its orbit when is farthest from the sun
3. The square of the orbital period of a planet is equal to the cube of its orbital distance p2 =d3

Question 16

What observations did Galileo make that supported the heliocentric model?

Answer 16

He used telescope observations to help confirm the heliocentric system
- looked at the Milky Way and discovered that it was made of stars
- also looked at moon and discovered craters
- Discover that Jupiter has moons (80 moon); and believed that if Jupiter has its own system of moons then earth is not the center of everything

Question 17

Explain each of newtons three laws of motion?

Answer 17

1st law: A body at rest remains at rest unless acted upon by an outside force h (e.g., a ball not moving until it is kicked ; Why we have seat belts in the first place)

2nd law: The acceleration of an object is directly proportional to applied force and inversely proportional to its mass (e.g., giant mass doesn’t go anywhere;smaller mass moves [force divided by mass] car accident)

3rd law:  for every force there is an equal force but opposite force (Something can keep going due to inertia but that could change one force acts on [sitting down on chair])

Question 18

What is inertia?

Answer 18

An objects natural tendency to resist changes in motion

Question 19

What is the difference between weight and mass?

Answer 19

Weight - is a measure of the gravitational force between two bodies; gravity can change weight

Mass - is a measure of the amount of material that makes up an object

Question 20

What is acceleration? When and why do planets accelerate? 

Answer 20

Change in speed vs. change in time; how fast velocity changes
-Planets change going faster & slower when accelerating and they constantly accelerate because there’s force acting on them

Question 21

What factors determine the strength of the gravitational pull between two objects?

Answer 21

mass and the distance between them (mass divided by the square of distance between them)

Question 22

What would happen to the force of gravity between two planets is there distance was cut in half? Or the doubled?

Answer 22

Mass and distance / how far away they are from each other

half = would increase four times stronger and closer

doubled = would decrease 1/4 stronger and become further away

Question 23

is there gravity in space?

Answer 23

Yes because astronauts are falling; weightless because they’re falling around earth

Question 24

Do all objects fall at the same rate?

Answer 24

Yes they do ignoring air resistance

Question 25

What is an orbit?

Answer 25

Going around earth never hits surface; falling down/weightless

Question 26

Why is an astronaut weightless while in orbit?

Answer 26

 orbit cancels out affect of earths gravity so this causes astronauts to enter a state of freefall/weightlessness

Question 27

What is escape velocity? What factors determine who escape velocity of the world?

Answer 27

Escape velocity - is the velocity needed to “escape” the gravity of an object

factors: depends on the mass of the object and your distance from it
- if an object is going fast enough it will leave earth forever (if it is it will end up in orbit or fall back)

Question 28

Who gave us a more complete theory of gravity? How was it different from Isaac newton ideas?

Answer 28

Albert Einstein (general relativity) - says massive objects bend in space
-Newtons idea of forces is accurate for most situations but Einsteins theory give the best explanation for gravity which is when space is warped the path of light is bent