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Flashcards in Lecture 2 Deck (46)
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1
Q

Is Andromeda our closest galaxy?

A

No, it is millions of ly away, outside the Milky Way

2
Q

What kind of object is Andromeda Galaxy?

A

An Extragalactic object

3
Q

How do we know Andromeda Galaxy will collide with us?

A

It has a radial velocity coming towards us, and no significant tangential velocity. All the stars we see are blue-shifted, which means they are coming towards us.

4
Q

Will the collision between us and Andromeda include any other galaxies?

A

Yes, the Triangulum Spiral

5
Q

What will happen to other stars once we collide with Andromeda?

A

They will not hit each other, but will change their orbits

6
Q

What is the definition of speed?

A

Rate at which object moves (SCALAR)

7
Q

What is the definition of velocity?

A

Rate at which object moves in a specific direction (VECTOR)

8
Q

What is the definition of acceleration?

A

Any change in velocity over time

9
Q

What did Galileo postulate about gravity?

A

All objects fall at the same rate (ignoring air resistance)

10
Q

What is the definition of Inertia?

A

A measure of an object’s resistance to change in motion

11
Q

What is an inertial frame?

A

An environment which allows us to estimate motion by observation, e.g. not a moving car, but the Princeton Campus

12
Q

What is Newton’s first law of motion?

A

object in motion will remain in motion unless acted on my a net unbalanced force

13
Q

What is Newton’s first law of motion re: momentum?

A

An object will maintain a constant momentum unless acted upon by an outside force.

14
Q

What is Newton’s Second Law of Motion?

A

F=ma; The acceleration of a body is parallel and directly proportional to the force acting on that body

15
Q

What is Newton’s third law of motion?

A

For every action force, there is an equal opposite reaction force

16
Q

What is the quantity used to represent inertial mass in rotational dynamics?

A

Moment of inertia

17
Q

What is angular momentum?

A

rotational velocity x rotational inertia; the measure of how hard it is to stop the rotating body

18
Q

What two factors effect angular momentum?

A

The distance from the axis and the mass of the rotating body

19
Q

Why do objects move at a constant speed if no force acts on them?

A

Because momentum is conserved

20
Q

How can the total momentum change?

A

By an external force acting on the objects

21
Q

How do individual objects change momentum?

A

Through equal and opposite force (Collisions)

22
Q

What is the parallel of force in rotational dynamics?

A

Torque

23
Q

Why does the earth not fall into the sun?

A

Gravitational force is not a torque, so it does not affect the orbit; it only stops the acceleration from allowing Earth to exit the orbit

24
Q

What is a Syzygy?

A

When three bodies align in a near-straight line

25
Q

What is appulse?

A

The closest apparent approach of two bodies

26
Q

What is conjunction?

A

When two bodies are in the same ecliptic plane

27
Q

What is the Greatest Elongation?

A

WHen one object is furthest from the sun or another object

28
Q

What is Opposition?

A

The greatest elongation when two bodies are opposite the sun

29
Q

What is a quadrature?

A

When two bodies make a right angle

30
Q

What is a transit?

A

When a smaller body passes in front of a larger body

31
Q

What is occultation?

A

When a larger body passes in front of a smaller body

32
Q

What is an eclipse?

A

When a body completely/partially disappears from view

33
Q

Which planet has the most angular momentum?

A

Jupiter

34
Q

What are the two different definitions of weight?

A
  1. gravity pulling down (Pushing up) 2. person’s gravity pulls up on the earth (pushing down)
35
Q

How does free-fall occur?

A

When you have gravity pulling down (Weight 1) and no person’s gravity pushing down (weight 2) you are in free-fall

36
Q

What are the two conditions required for an eclipse?

A
  1. a new moon (solar) or full moon (lunar) 2. the moon must be at one of the nodes of its orbit
37
Q

What are the nodes of the moon’s orbit?

A

points where the moon’s slightly tilted orbit crosses the earth’s ecliptic orbit; happens not quite every six months

38
Q

What are the three main types of energy?

A

Kinetic, Radiative, Potential

39
Q

What is radiative energy?

A

Energy that is emitted in the form of light / heat

40
Q

What is the umbra?

A

The point in an eclipse where the sunlight is completely blocked

41
Q

What is the penumbra?

A

The point in the eclipse where the sunlight is partially blocked

42
Q

What is the totality?

A

WHen the sunlight is completely blocked during an eclipse

43
Q

When does a total solar eclipse occur?

A

When the moon is especially close to the earth, and creates a large shadow

44
Q

When does an annuler eclipse occur?

A

When the moon is especially close to the earth, and the umbra does not even reach the earth

45
Q

When does a partial solar eclipse occur?

A

When only part of the sun is blocked

46
Q

What is the Saros Cycle

A

The calculations used to predict when eclipses will occur