Astrophysics

Question 1

Define a universe

Answer 1

Contains everything that there is

Created by the big bang 13.7 billion years ago

expanding faster than the speed of light

Question 2

Define galaxy

Answer 2

10 to the power of 11 in our universe

Collection of billions of stars

We are in the Milky way

Question 3

Define stars

Answer 3

Made of hydrogen

Nuclear fusion of H to He

Question 4

Define Solar systems

Answer 4

Everything that orbits our sun is part of our solar system

Question 5

What are satellites

Answer 5

Anything that orbit a planet

Question 6

How do satellites orbit

Answer 6

Orbit in circles around planets

Question 7

How do planets orbit

Answer 7

Slightly elliptical around stars

Question 8

How do comets orbit

Answer 8

Highly elliptical around stars they speed up when closer due to the gravitational force

Question 9

Give the weight mass gravity equation

Answer 9

w = m x g

Question 10

Every object has a ……………..field around it. The field strength is………for larger masses.

Answer 10

Gravitational

Larger

Question 11

What is weight measured in

Answer 11

N

Question 12

What is the orbital speed equation

Answer 12

v = 2πr ÷ T

Question 13

Orbital speeds are usually measured in….

Answer 13

Km/s

Question 14

Stars have different……….. , …………and………….

Answer 14

Colours, sizes and brightnesses

Question 15

What are stars grouped by

Answer 15

Their colours

Question 16

What colour will a hot and cold star be

Answer 16

Hot = Blue

Cold = Red

Question 17

Describe the birth of a star

Answer 17

Nebula = a cloud of gas and dust. It compresses due to gravitational forces that attract all the particles together

Fusion begins = The nebula heats up and pressure increases and starts to glow. This heats up further, eventually at 10 million kelvin, fusion begins

Main sequence stars = when the star becomes stable it’s called a main sequence star
Radiation pressure = gravitational force
H fuses to He

Solar System = Unused material around the star is grouped together to form planets, comets, etc.

Question 18

Describe the life of a star

Answer 18

Nebula collapses due to gravity

It heats up and fusion begins
Pressure increases

Main sequence star = stable

Eventually hydrogen runs out, star compresses because gravitational force is greater than radiation pressure. temperature + pressure increase, fusion of helium begins. The star swells to a massive size. The surface is cooler so it appears red.

Eventually helium runs out. Gravitational force dominates again, compressing the star and heating it up but not enough to fuse Carbon. It now glows white and is called a white dwarth. They are millions of times denser than anything on Earth

As the c
dead star cools, the colour changes to black

Question 19

Describe the life of a big star

Answer 19

Nebula collapses due to gravity

Heats up,pressure increases and fusion begins

Main sequence star stable due to radiation pressure = gravitational force

When hydrogen runs out the star fuses all the elements up to iron. It swells to an ENORMOUS size called a super Red Giant

When fuel finally runs out it collapses and explodes = Super Nova

The core that remains is EXTREMELY dense!!
Neutron star

If the star was massive the core would be even denser, gravity cannot escape = black hole

Question 20

What two things does the brightness of a star depend on

Answer 20

Luminosity (power output)

Distance from Earth

Question 21

The brightness of a star is called it’s…………………..

Answer 21

Apparent magnitude

Question 22

What is Absolute Magnitude

Answer 22

Compares all the stars as if they would appear at a set distance from Earth

Question 23

Describe the birth of the universe

Answer 23

All the matter and all the energy in the universe started from a suer small, hot, dense point called a singularity that suddenly exploded about 13.8 billion years agoIt has been expanding ever since

Question 24

What is the doppler effect

Answer 24

if the source of a wave is moving towards us, then the wavelength is compressed. for light waves this is called blue shift. If the source is moving away then the wavelength is stretched and called red shift. This can happen with sound

Question 25

What si the equation for the doppler effect

Answer 25

λ - λ
—————– = v/c
λ 0

Question 26

What is C

Answer 26

Speed of light

3x10 to the power of 8

Question 27

The faster something moves the greater the…………

Answer 27

Red shift