Solar system; stability of orbital motions; satellites (8.1) (M)

Question 1

What is the universe?

Answer 1

a large collection of galaxies

Question 2

Within our solar system, how many stars are there?

Answer 2

1 - the Sun

Question 3

Within our solar system, how many planets are there?

Answer 3

eight

Question 4

Other than the star and planets in our solar system, what are the other components of our solar system?

Answer 4

dwarf planets and natural satellites

Question 5

What do planets and dwarf planets do in our solar system?

Answer 5

orbit around the Sun

Question 6

What are natural satellites?

Answer 6

moons that orbit planets

Question 7

Our solar system is a (…) part of the (…) galaxy

Answer 7

small

Milky Way

Question 8

How was the Sun formed?

Answer 8

a cloud of dust and gas (nebula) was pulled together by gravitational attraction

Question 9

What is the order of the planets?

Answer 9

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, (Pluto)

My Very Excellent Mum Just Served Us Noodles

Question 10

What is a nebula?

Answer 10

a cloud of gas and dust

Question 11

How does a star begin fusion?

Answer 11

Gravity pulls together the dust and gas.

Once it is hot and dense enough at the centre of a mass, then fusion can start.

This leads to a force - radiation pressure - pushing outwards (expansion of the star)

Question 12

What is the life cycle of a star determined by?

Answer 12

the size of the star

Question 13

What is the life cycle of a star the size of the sun? (in simple stages)

Answer 13

Nebula ⇢ Protostar ⇢ Main Sequence Star ⇢ Red Giant ⇢ White Dwarf ⇢ Black Dwarf

Question 14

What is the life cycle of a star much bigger than the sun? (in simple stages)

Answer 14

Nebula ⇢ Protostar ⇢ Main Sequence Star ⇢ Super Red Giant ⇢ Supernova ⇢ Neutron Star

Question 15

What is the life cycle of a star much, much, much bigger than the sun? (in simple stages)

Answer 15

Nebula ⇢ Protostar ⇢ Main Sequence Star ⇢ Super Red Giant ⇢ Supernova ⇢ Black Hole

Question 16

How did a protostar form from a nebula?

Answer 16

gravity pulled together the cloud of gas and dust

The particles in the cloud got faster and collided more.

The gas warmed up and eventually became hot
enough to glow.

Question 17

How does a main sequence star form from a protostar?

Answer 17

As the protostar gets more dense, more collisions take place and it gets hotter.

Eventually the cloud gets hot enough for hydrogen atoms to fuse, forming helium.

Question 18

How long is a star in the main sequence stage for?

Answer 18

Most of its life

Question 19

When does a red giant form?

Answer 19

When the star runs out of hydrogen to fuse

Question 20

How does a red giant form form a main sequence star?

Answer 20

When a star starts to run out of hydrogen to fuse, it expands and the star will become a red giant

Question 21

What fusion takes place in a red giant?

Answer 21

helium and other light elements in the core fuse to form heavier elements

Question 22

When does fusion stop in the red giant?

Answer 22

When there are no more light elements in the core

Question 23

How does a white dwarf form from a red giant?

Answer 23

When there are no more light elements in the core, fusion stops and no more radiation is released.

The star contracts to become a white dwarf

Question 24

What is the size difference between the red giant and white dwarf?

Answer 24

The white dwarf is much smaller

Question 25

What is the stage after the white dwarf phase? How does this happen?

Answer 25

The stars eventually fade out becoming black dwarfs

Question 26

Why does a supernova explosion take place?

Answer 26

The stars have more mass and so the collapse is more violent

Question 27

What happens in a supernova?

Answer 27

The core collapses in on itself, and then a burst of bright light quickly spreads from the core releasing elements heavier than iron across space

Question 28

How does a supernova become a neutron star?

Answer 28

The supernova explosion compresses the core into a neutron star

Question 29

What is a neutron star?

Answer 29

An extremely dense object made only of neutrons.

Question 30

Why will planets in a solar system with a white dwarf freeze out?

Answer 30

No fusion takes place and so no heat radiation is released from the star

Question 31

Describe a black hole? (in relation to gravitational field)

Answer 31

The gravitational field of a black hole is so strong nothing can escape from it, not even light.

Question 32

What do fusion processes in stars produce?

Answer 32

all of the naturally occuring elements

Question 33

What elements are produced in a supernova?

Answer 33

Elements heavier than iron

Question 34

What does a supernova do?

Answer 34

The explosion of a massive star (supernova) distributes the elements throughout the universe

Question 35

What is nuclear fusion?

Answer 35

The joining of two light nuclei to form a heavier nucleus (like a new element)

Question 36

What happens to some of the mass in nuclear fusion?

Answer 36

Some of the mass may be converted into the energy of radiation

Question 37

How does nuclear fusion apply to stars?

Answer 37

It is how stars release energy when hydrogen atoms fuse to make helium

requires very high temperatures and pressures, hard to replicate and would be costly

Question 38

How do planets and satellites maintain their circular orbits?

Answer 38

Gravity provides the force that allows planets and satellites (both natural and artificial) to maintain their circular orbits

For something to move in a circle there must be a force acting towards the centre of the circle.

Question 39

How does a satellite in circular orbit at constant speed accelerate?

Answer 39

Gravity (from the centre of mass of the planet) is acting on the satellite, pulling it towards Earth, so it must be accelerating.

Acceleration is the rate of change of velocity.

If something is changing direction then its velocity is changing, even if the speed is staying the same

Question 40

What are the two types of satellites?

Answer 40

artificial and natural

Question 41

If the speed of the satellite increases, the radius of its orbit (…)

Answer 41

decreases

Question 42

Why must the radius of the orbit decrease if the satellite moves faster?

Answer 42

At a higher speed, the satellite needs a greater force of gravity acting on it to remain in stable circular orbit and prevent it from flying into space

True for planets as well

Question 43

What are 3 factors that affect the size of the resultant force acting on a satellite?

Answer 43

• radius of orbit
• speed
• mass

Question 44

6 marker

Describe the life cycle of a star much more massive than the sun, including the formation of new elements

Answer 44

• fusion (processes in stars) produce new elements
  • cloud of gas / hydrogen and dust OR nebula
  • pulled together by gravity
  • causing increasing temperature (to start the fusion process) • (to become a) protostar
• hydrogen nuclei fuse to form helium nuclei
• and the star becomes main sequence
• hydrogen begins to run out
• helium nuclei fuse to make heavier elements • uptoiron
• the star expands (to become a)
• red super giant
• (the star collapses rapidly) and explodes
• called a supernova
• creating elements heavier than iron
• and distributing them throughout the universe • leaving behind a neutron star
• or a black hole.

Question 45

Why does the velocity of a satellite change as it orbits the Earth?

Answer 45

force of gravity causes the satellite to accelerate towards Earth

this acceleration causes a change in direction

velocity is a vector so changes because direction changes

Question 46

Why can scientists not answer the question: why was the universe created?

Answer 46

always involves religious belief

Question 47

The solar system contains many heavy elements, what does this tell us about the age of our solar system?

Answer 47

It is younger (so not formed at time of big bang)

as nuclear fusion in a supernova must have occurred relatively recently

Question 48

What is required for a star to remain in the main sequence stage?

Answer 48

inward force of gravity balanced by outward force of radiation pressure which causes expansion, these 2 forces are in equilibrium

there is sufficient hydrogen to last a very long time

Question 49

3 marks

How are elements other than hydrogen formed?

Answer 49

Nuclear fusion leads to hydrogen fusing to form helium

elements heavier than iron only produced in nuclear fusion

of lighter elements in a supernova

nuclear fusion in supernova is between lighter elements than those produced

Question 50

What is the relationship between the masses of dust and gas in the cloud and the force of gravity between them?

Answer 50

The greater the mass of dust and gas in the cloud, the larger the size of the force of gravity between them

Question 51

What is the relationship the distance apart of the dust and gas particles in the cloud and the size of the force of gravity between them?

Answer 51

the greater the distance apart of the dust and gas particles in the cloud, the lower the size of force of gravity

Question 52

Why might the mass of the star increase as core temperature over time progresses?

Answer 52

greater core temperature means greater rate of fusion

Question 53

Describe the life cycle of a star the size of the sun

Answer 53

• formed from cloud of gas and dust (nebula)
• pulled together by gravity
• massive so very large gravitational forces (pulling inwards)
• hydrogen atoms fuse to form helium in nuclear fusion (which releases energy)
• high temperature creates high pressure pushing outwards
• long period when forces balance
• then expands → red giant
• then contracts (under the force of gravity) to dense white dwarf
• then fades to become black dwarf

Question 54

3 needed

What factors affect the size of gravitational attraction on a satellite?

Answer 54

• mass of satellite
• speed/velocity of satellite
• radius of orbit