Astophysics

Question 1

What does the Solar System consist of?

Answer 1

8 planets
Natural satellites (eg: Moon)
Dwarf planets (eg: Pluto)
Asteroids
Comets

Question 2

What are the characteristics of a planet

Answer 2

Orbits the sun
Not a moon
Enough mass to be round
Able to clear its orbit of debris

Question 3

What determines the shape of galaxies?

Answer 3

Gravitational force

Question 4

How does mass and distance affect gravitational force

Answer 4

Less mass means less gravitational force
More mass means more gravitational force
Less distance means more gravitational force
More distance means less gravitational force

Question 5

Gravitational forces cause

Answer 5

Planets and comets to orbit the Sun (elliptical)
Moons and Satellites to orbit Earth (circular)
Stars to orbit the centre of their galaxy

Question 6

What are 2 types of Satellites

Answer 6

Natural (Moon)
Artificial

Question 7

What is Circular Motion

Answer 7

For an object to move in a circle, there must be a force that acts on the object which pulls it to the centre of its circular path
Gravitational force between the Sun and the planets or the Earth and the moon provides this force
Because the object’s direction is constantly changing, the velocity is changing, because velocity is a vector

Question 8

What are comets and what type of orbits do they follow

Answer 8

It is a body made of dust and ice
Very Elliptical orbits which at times are very close to the Sun and other times travel to the very edge of the solar system

Question 9

As a comet approaches the Sun..

Answer 9

Gravitational force gets stronger
Kinetic energy increases because its travelling faster
It loses gravitational potential
When closest to the Sun, KE is maximum and GPE minimum

Question 10

What is the equation for orbital speed

Answer 10

Orbital Speed= Orbital radius * 2pi / Time

Question 11

What are the colours, temperature and spectral class of the hottest and least hottest stars?

Answer 11

Hottest- Blue, 30 000+, O
Least Hottest- Orange-red, 2400-3700, M

Question 12

What are 3 ways stars are classified in terms of brightness

Answer 12

Apparent brightness or magnitude of a star as seen from Earth
The absolute brightness or magnitude of a star if placed a certain distance: 10 parsecs or 32.6 light years
The luminosity of a star- amount of energy as light is emitted from the stars surface every second

Question 13

Explain the magnitude scale and state the star used to define an apparent magnitude of 0

Answer 13

In middle brightness, brightness is 0
In brighter stars magnitude is negative
In duller stars the magnitude positive
Brightness of the star Vega is used to determine the magnitude of 0

Question 14

Describe the life process of a star the size of our sun

Answer 14

Starts off as a nebula
Then a Protostar
Then a Main sequence star
Then a Red giant star
Then a White dwarf
Then a Black dwarf

Question 15

Describe the life process of a star much bigger than our sun

Answer 15

Starts off as a nebula
Then a Protostar
Then a Main sequence star
Then a Red super giant star
Then a Supernova
Then a neutron star or black hole

Question 16

What is on the y-axis, x-axis of a star in a HR diagram

Answer 16

y-axis: absolute magnitude (dim at bottom, bright at top)
x-axis: Temperature of star (hot on left, cold on right)-opposite to normal

Question 17

Use the HR- diagram
1. What are the loudest and coolest stars

Answer 17

1. Red supergiants

Question 18

What are 3 types of spectra, explain each one

Answer 18

Continuous spectrum:
Emission spectrum
Absorption spectrum

Question 19

What is the doppler equation