Physics test 4

Question 1

What is the idea behind the geocentric model?

Answer 1

the idea behind the geocentric model is that the earth is the center of the universes and everything orbits around us

Question 2

What is the idea behind the heliocentric model?

Answer 2

the idea behind the heliocentric model is that the sun was the center of the solar system

Question 3

How did the invention of the telescope support the heliocentric model?

Answer 3

with the telescope astronomers found object which were much further away and found 4 of Jupiter’s moons . by plotting there movements, he showed that not everything orbited the earth

Question 4

How does a elliptical orbit look like?

Answer 4

a oval / squashed circle

Question 5

What is a natural satellite?

Answer 5

a moon

Question 6

Why are some telescopes which are meant to detect certain electromagnetic waves placed in orbit?

Answer 6

because the atmosphere absorbs some of the radiation they are designed to detect.

Question 7

What is weight?

Answer 7

weight if the force of gravity acting on you

Question 8

What are the two factors which affect ones weight?

Answer 8

Your weight depends on your mass and the gravitational field strength.

Question 9

What is the Gravitation field strength of earth?

Answer 9

10

Question 10

What is the formula to calculate the Gravitation field strength of a plant/moon?

Answer 10

Mass of planet/radius

Question 11

What affects the Gravitation field strength of a plant/moon?

Answer 11

It depends on the mass of the body and the distance from its center to its surface(its radius). The greater the mass and the smaller the radius the greater its surface gravity

Question 12

What are some uses of artificial satellites?

Answer 12

to observe the earth and for communication

Question 13

What is the use of satellites that are in highly elliptical orbits?

Answer 13

Communication in parts of the earth near the poles

Question 14

What does geostationary orbit mean?

Answer 14

it remains over one point on earth

Question 15

What is the use of artificial satellites in a circular geostationary orbit ?

Answer 15

They are use for broadcasting.

Question 16

What is the speed in which satellites in a circular geostationary orbit move at?

Answer 16

3070m/s

Question 17

Describe 3 different types of orbits that artificial satellites can be put into.

Answer 17

Circular geostationary orbit which remains over a single point on earth

Highly elliptical orbits which travel near the poles of the earth

Polar orbit which the satellite will pass of over every point on earth

Question 18

What is a nebula?

Answer 18

a cloud of dust and gasses mainly hydrogen

Question 19

How does a protostar form?

Answer 19

the hydrogen gets pulled together by their own gravity. as the cloud contracts and becomes denser. the hydrogen becomes hotter and spirals inwards and may start to glow. as more mase attracts the cloud gravitation pull gets stronger and heats the material even more

Question 20

What is a fusion reaction?

Answer 20

when elements are forced due to high temperature and pressure to fuse together.

Question 21

How is the main sequence star formed?

Answer 21

Once the temperatures and pressures in the center of the protostar are high enough to force hydrogen nuclei to fuse together and form helium. Fusion reactions like this release a lot of energy as electromagnetic radiation. The outward pressure from the hot gases just balances the compression due to gravity.

Question 22

In what stage is our sun in now?

Answer 22

is in the main sequence star part of its life cycle

Question 23

For stars with similar sizes to our sun , how long are they stable for?

Answer 23

10billion years

Question 24

What happens when all the hydrogen has been formed into helium?

Answer 24

once that has happened the core is not hot enough to withstand gravity and it collapses. the outer layer expands to form a red giant star, much larger than the original star.

Question 25

how long are red giants stable for?

Answer 25

a billion years

Question 26

How is a white dwarf formed?

Answer 26

after being stable for a billion years the red supergiant releases a shell of gas. the rest of the star is pulled together by gravity and collapses to form a white dwarf.

Question 27

What are the main differences between a normal life cycle of our sun and the life cycle of of a massive star?

Answer 27

They burn much hotter than the sun and fuse hydrogen into helium faster, instead of forming red giant it forms red Supergiant and at the end when the supergiant collapses it forms a supernova instead of a white dwarf.

Question 28

What are the two possible outcomes of a supernova and how is it decided which one is formed?

Answer 28

if what is left is 4 or more times the mass of the sun, gravity pulls the remains together to form a black whole
if the remains are not massive enough to form a black hole, gravity pulls them together to form a small star called a neutron star

Question 29

What is the doppler effect?

Answer 29

The doppler affect

Question 30

How does red shift work?

Answer 30

if they are moved towards the red und of the spectrum it means the star is moving away from us. The further the lines are shifted the faster it is moving away

Question 31

How is the blue shift measured?

Question 31

How is the red shift measured?

Answer 31

It is measured by how far along the spectrum the lines have moved

Question 32

How is the blue shift measured?

Answer 32

It is measured by how far along the spectrum the lines have moved

Question 33

How does red shift prove the universe is expanding?

Question 34

What is the Big Bang theory?

Answer 34

the Big Bang theory states that the whole universe and all the matter in it started out as a tiny point of concentrated energy about 13.5 billion years ago. the universe expanded from that point and is still expanding.as the universe expanded gravity caused matter to clump together to form stars

Question 35

What is the steady state theory?

Question 36

What does the CMB stand for?

Question 37

What is the CMB?