Astrology Flashcards
What is the distance from Earth to the sun known as?
1AU (1 astronomical unit)
What is the value of 1AU in metres?
1.5x10^11 m
How long does it take light from the sun to reach Earth? In seconds & minutes.
500 seconds & 8 mins
What is a solar mass & its quantity?
The mass of the sun (2x10^ 30 kg)
Where is most of the mass of the solar system?
The sun, the mass of the sun is much greater than that of all the planets combined.
What word is used to describe the motion of the Sun?
Rotational
What equation is associated with the motion of the Sun?
L = Iω (L = angular momentum, I = moment of inertia & ω = angular frequency)
What word is used to describe the motion of a planet?
Orbital
What equation is associated with the motion of planets?
L = rp (L = angular momentum, r = radius of orbit & p = momentum where p=mv)
Where is most of the angular momentum of the solar system held?
The planets have a lot more angular momentum than the sun.
Why are stars so much fainter than the sun?
Due to the inverse square law.
What is the difference between luminosity & flux?
L = Luminosity ( J s^-1 ) is the light EMITTED per second
F = Flux ( J s^-1 m^-2 ) is the light RECIEVED per unit area per second
What is the definition & quantity of a light year?
Distance light travels in a vacuum in a year ~ 9.5x10^15 m
What angle does the sun subtend?
0.5 degrees
What is an arcminute?
1’ = 1/60 degree
What is an arcsecond?
1” = 1 / 3600 degree
What is the definition & quantity of a parsec?
Distance at which 1AU subtends 1” (arcsecond) ~ 3.1x10^16 m
Approximately the distance to the nearest stars
What is Keplers 1st law?
Planets travel in elliptical orbits with the sun at one focus
What is the semi major axis, a?
It is half of the longest diameter of an ellipse
What is a aphelion?
The point in the orbit of Earth when it is farthest from the Sun
What is a perihelion?
The point in the orbit of the Earth when it is closest to the Sun
What is Kepler’s 2nd law?
A line connecting a planet to the sun seeps out equal areas in equal time (planets move faster when they are closer to the sun)
What is keplers 3rd law?
The orbital period (P) squared is directly proportional to the average distance from the sun (a- semi major axis) cubed
What is newtons 1st law?
In the absence of force, objects travel in a straight line with constant velocity, no net force means no acceleration
What is newtons 2nd law?
A force applied to a body produces an acceleration proportional to its mass F=ma
What is newtons 3rd law?
Every action has an equal and opposite reaction
