paper 2 : space physics

Question 1

in order of closest to furthest away from the sun, how is our solar system arranged

Answer 1

the order of the planets from closest to furthest away from the sun is :

• mercury
• venus
• earth
• mars
• jupiter
• saturn
• uranus
• neptune

Question 2

how do all star’s life cycles begin

Answer 2

all star’s life cycles begin with a a large cloud of dust and gas which is held together by gravity

Question 3

how was the sun formed

Answer 3

the sun was formed from a cloud of dust and gas,also called a nebula, which was brought together by gravitational attraction

Question 4

describe the first stages of the life cycle of a star

the same for stars bigger than the sun and stars the same size as the sun

Answer 4

the first stages of a stars life cycle are :

• there is a large cloud of dust and gas (nebula), and gravitational attraction pulls in more dust and gas
• the dust and gas builds up, turning the nebula into a ball of hydrogen gas; a protostar
• due to the protostar’s gravitational attraction, nuclear fusion begins and the hydrogen atoms begin to fuse together to form helium nuclei; here it is called the main sequence star

Question 5

after the first stages of the stars life cycle, what can a star which is the same size as the sun, become

Answer 5

after the first stages of the stars life cycle, a star which is the same size as the sun can become a :

• red giant
• white dwarf
• black dwarf

Question 6

after the first stages of the stars life cycle, what can, a star which is bigger than the sun, become

Answer 6

after the first stages of the stars life cycle, a star which is bigger than the sun can become a :

• red super giant
• super nova
• black hole or a neutron star

Question 7

what is important to remember about the life cycle of star which is either the same size as the sun or bigger than the sun

Answer 7

it is important to remember that in the life cycle of a star which is either the same size as the sun or bigger than the sun,that the first stages; nebula, protostar and main sequence star, are EXACTLY THE SAME

Question 8

in the life cycle of a star BIGGER than the sun, what happens after the first stages

Answer 8

in the life cycle of a star BIGGER than the sun, after the first stages :

• the main sequence star cools and expands, as its source of fuel (hydrogen) runs out. it forms a RED SUPER GIANT and elements form, with iron being the heaviest
• next the red super giant runs out of fuel(hydrogen) and then collapses under the force of gravity and explodes into a SUPER NOVA which results in elements heavier than iron forming and more dust and gas getting thrown into space
• after the supernova, whats left is either a BLACK HOLE or a NEUTRON STAR

Question 9

in the life cycle of a star that is the SAME size as the sun, what happens after the first stages

Answer 9

in the life cycle of a star that is the SAME size as the sun, after the first stages :

• the main sequence star runs out of hydrogen,which was its fuel. the star cools and expands to form a RED GIANT
• the red giant then collapses under the force of gravity leaving a WHITE DWARF. in a white dwarf, there is now fusion occurring
• eventually the white dwarf will cool down even more to become a BLACK DWARF; which is cold,small and has no fusion occurring

Question 10

why does the main sequence star stay the same size for billions of years

Answer 10

the main sequence star stays the same shape for billions of years, as there is a balance between gravity pulling inwards and the pressure from fusion pushing. outwards

Question 11

how is a nebula formed

Answer 11

a nebula is formed from either :

• left over dust and gas which has been thrown out into space from a supernova
• the big bang

Question 12

why do scientists think that the world was formed from a super nova rather than from the big bang

Answer 12

scientists think that the world was formed from a super nova rather than from the big bang because on earth there are naturally occurring elements which a heavier than iron

Question 13

what are some examples of natural satellites

Answer 13

examples of natural satellites are :

• moons
• planets(orbit the sun)
• asteroids

Question 14

why do planets and satellites(artificial and natural) stay in their orbits

Answer 14

planets and satellites(artificial and natural) are able to stay in their orbits due to the force of gravity

Question 15

what are the similarities between planets, planets moons and satellites

Answer 15

the similarities between planets, planets moons and satellites are :
-they’re all held in the orbit by the force of gravity

Question 16

why, in a circular orbit, does the force of gravity lead to changing velocity but unchanged speed

Answer 16

in a circular orbit, the force of gravity leads to changing velocity but unchanged speed as :

• although the satellites speed is constant, the satellite is also constantly changing direction due to the fact that it is in a circular orbit and the force of gravity is acting upon it
• this means that it is also constantly accelerating and as velocity is a vector quantity, the change in direction means a change in velocity but no change in speed

Question 17

why, in a stable orbit, must the distance from the satellite to the planet or star (radius) change, if the speed of that satellite increases

Answer 17

in a stable orbit, the distance from the satellite to the planet or star (radius) must change, if the speed of that satellite increases as :

• the closer to the planet or star, the stronger the force of gravity
• if a satellite’s speed is very big, a stronger force will be needed to keep the satellite in its orbit, therefore the radius must be decreased so that there is smaller distance between the star or planet and the satellite

Question 18

why, in a stable orbit, must the distance from the satellite to the planet or star (radius) change, if the speed of that satellite decreases

Answer 18

in a stable orbit, the distance from the satellite to the planet or star (radius) must change, if the speed of that satellite decreases as :
- if the radius was very small, the force of gravity would be too much and the satellite could fall down to the planet/star therefore, if the satellites speed is slow, it must have a greater radius so the force of gravity is less

Question 19

what is red shift

Answer 19

red shift is the increase in wavelength of light as distance of galaxies increases, the further away the galaxy, the larger the wavelength of light

Question 20

how does red shift give evidence for the big bang

Answer 20

red shift provides evidence for the big bang as :

• the big bang theory suggests that the universe was created from a SMALL,HOT DENSE region which ‘exploded’ and began to inflate/expand
• scientists have discovered that certain galaxies are getting further away from each other, compared to data from previous years, which suggests the universe is still expanding

Question 21

why can’t scientists be sure that red shift showing the universe is expanding, is proof for the big bang theory

Answer 21

scientists can’t be sure that, red shift showing the universe is expanding, is proof for the big bang theory as they believe the universe is made up the dark matter and dark energy. they also think that dark energy may be responsible for the accelerated expansion of the universe

Question 22

what is dark matter

Answer 22

dark matter is the name given to an unknown substance which is believed to hold galaxies together and doesn’t emit electromagnetic radiation

Question 23

what have observations of supernovae in 1998 and onwards suggested to scientists

Answer 23

observations of supernovae in 1998 and onwards suggested to scientists that the speed at which galaxies are receding, is increasing; they’re getting further away quicker