astrophysics dbl

Question 1

what is a universe

Answer 1

large collection of billions of galaxies

Question 2

galaxy

Answer 2

a large collection of billions of stars

Question 3

our solar system is in what galaxy

Answer 3

the milky way

Question 4

what is at the centre of our solar system

Answer 4

the sun

Question 5

gravitational field strength varies how

Answer 5

strength of gravity in different planets affects an objects weight on that planet

Question 6

weight

Answer 6

force acting on an object due to gravitational attraction

Question 7

fore of weight is responsible for (3)

Answer 7

• objects staying firmly on the ground
• objects always falling to the ground
• satellites being kept in orbit

Question 8

gravitational field strength depends on (2)

Answer 8

mass (greater the mass, greater the g)
distance from its centre (closer you are the stronger it is)

Question 9

g on earth

Answer 9

10 N/Kg

Question 10

higher gravitational field strength means

Answer 10

a larger force of attraction towards the centre of the planet or moon

Question 11

does the mass of an object vary

Answer 11

no

Question 12

does the weight of an object vary

Answer 12

yes depending on what planet its on, gravitational field strength

Question 13

why does gravitational field strength vary (2)

Answer 13

as you move further away from a planet, gravity decreases

bigger mass= stronger gravity

Question 14

smaller/larger bodies orbit smaller/larger bodies

Answer 14

smaller

larger

Question 15

planets orbit the

Answer 15

sun

Question 16

moons orbit the

Answer 16

planets

Question 17

comets orbit the

Answer 17

sun

Question 18

artificial satellites orbit the

Answer 18

earth

Question 18

orbital motion is a result of

Answer 18

the gravitational force of attraction acting between 2 bodies.

Question 19

asteroids orbit the

Answer 19

sun

Question 20

gravitational force always acts in what direction

Answer 20

towards the centre of the larger body, causing smaller body to move in a circular motion

Question 21

similarities in the way different planets orbit the sun (3)

Answer 21

• all orbit on the same plane
• all travel in the same direction
• orbits are all slightly eliptical

Question 22

differences in the way different planets orbit the sun (3)

Answer 22

• orbit at different distances from the sun
• orbit at different speeds
• all take different amounts of time to orbit the sun

Question 23

planets closest to sun take how long and why

Answer 23

shortest amount of time as they are the fastest

Question 24

planets furthest from the sun take how long to orbit sun and why

Answer 24

longest amount of time as they travel at slowest speeds

Question 25

orbital motion of moons (3)

Answer 25

- orbit in circular path - some planets have more than one moon - the closer the moon to the planet, the shorter the time taken to complete and orbit and the greater the speed

Question 26

orbital motion of comets (3)

Answer 26

highly eliptical as comet approaches sun, speed increases as it moves further away from the sun, its speed decreases

Question 27

the comets orbital motion are highly eliptical, so?

Answer 27

speed changes significantly as their distance from the sun changes

Question 28

do all comets orbit in the same plane

Answer 28

no, some don't even go in the same directions

Question 29

what causes artificial satellites to orbit the earth

Answer 29

the gravity of the earth keeps them in orbit, and they're launched at high speeds and gravity bends their path into a continuous curved orbit around the sun

Question 30

what is an orbital period

Answer 30

time taken for an object to perform one orbit

Question 31

extremely hot objects emit what radiation what does this mean

Answer 31

visible light and infrared which means that the colour they emit depends on how hot they are

Question 32

red star is

Answer 32

coolest

Question 33

blue star is

Answer 33

hottest

Question 34

colour of a star is related to its

Answer 34

surface temperature

Question 35

as astronomical objects cool, they

Answer 35

expand

Question 36

as astronomical objects heat, they

Answer 36

contract

Question 37

when a star becomes a red giant, it does what

Answer 37

expands, cools and becomes redder

Question 38

when a star becomes a white dwarf, it

Answer 38

contracts, heats up and gets whiter

Question 39

life cycle of solar mass stars

Answer 39

stellar nebula → protostar → main sequence star - THEN EITHER STARS WITH MASS LOWER THAN SUN, OR STARS WITH MASS LARGER THAN SUN

Question 40

nebula

Answer 40

a large interstellar cloud of dust and gas

Question 41

how does a protostar form

Answer 41

The force of gravity within a nebula pulls the particles closer together until a hot ball of gas forms, known as a protostar As the particles are pulled closer together the density of the protostar will increase This results in more frequent collisions between the particles which causes the temperature to increase

Question 42

how does a main sequence star form

Answer 42

Once the protostar becomes hot enough, nuclear fusion reactions occur within its core Once a star initiates fusion, it is known as a main-sequence star During the main sequence, the star is in equilibrium and said to be stable

Question 43

low mass star cycle

Answer 43

red giant → planetary nebula → white dwarf

Question 44

red giant forms how

Answer 44

After several billion years, the hydrogen causing the fusion reactions in the star will begin to run out Once this happens, the fusion reactions in the core will start to die down The star will begin to fuse helium which causes the outer part of the star to expand As the star expands, its surface cools and it becomes a red giant

Question 45

white dwarf forms how

Answer 45

Once the helium fusion reactions have finished, the star collapses and becomes a white dwarf The white dwarf cools down over time and as a result, the amount of energy it emits decreases

Question 46

larger mass cycle

Answer 46

red supergiant → supernova → neutron star / black hole

Question 47

key differences between lower mass and larger mass stars

Answer 47

A higher mass star will stay on the main sequence for a shorter time before it becomes a red supergiant A lower mass star fuses helium into heavy elements, such as carbon, whereas a higher mass star fuses helium into even heavier elements, such as iron

Question 48

red supergiant forms how

Answer 48

After several million years, the hydrogen causing the fusion reactions in the star will begin to run out Once this happens, the fusion reactions in the core will start to die down The star will begin to fuse helium which causes the outer part of the star to expand As the star expands, its surface cools and it becomes a red supergiant

Question 49

supernova forms how

Answer 49

Once the fusion reactions inside the red supergiant cannot continue, the core of the star will collapse suddenly and cause a gigantic explosion called a supernova At the centre of this explosion, a dense body called a neutron star will form The outer remnants of the star are ejected into space forming new clouds of dust and gas (nebula) The heaviest elements are formed during a supernova, and these are ejected into space These nebulae may form new planetary systems

Question 50

neutron star is formed how

Answer 50

forms when a massive star explodes in a supernova and its core collapses, compressing into an extremely dense ball of neutrons.

Question 51

what happens to neutron stars

Answer 51

in the case of the most massive stars, the neutron star that forms at the centre will continue to collapse under the force of gravity until it forms a black hole A black hole is an extremely dense point in space that not even light can escape from