Physics test 4 Flashcards
What is the idea behind the geocentric model?
the idea behind the geocentric model is that the earth is the center of the universes and everything orbits around us
What is the idea behind the heliocentric model?
the idea behind the heliocentric model is that the sun was the center of the solar system
How did the invention of the telescope support the heliocentric model?
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
How does a elliptical orbit look like?
a oval / squashed circle
What is a natural satellite?
a moon
Why are some telescopes which are meant to detect certain electromagnetic waves placed in orbit?
because the atmosphere absorbs some of the radiation they are designed to detect.
What is weight?
weight if the force of gravity acting on you
What are the two factors which affect ones weight?
Your weight depends on your mass and the gravitational field strength.
What is the Gravitation field strength of earth?
10
What is the formula to calculate the Gravitation field strength of a plant/moon?
Mass of planet/radius
What affects the Gravitation field strength of a plant/moon?
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
What are some uses of artificial satellites?
to observe the earth and for communication
What is the use of satellites that are in highly elliptical orbits?
Communication in parts of the earth near the poles
What does geostationary orbit mean?
it remains over one point on earth
What is the use of artificial satellites in a circular geostationary orbit ?
They are use for broadcasting.
What is the speed in which satellites in a circular geostationary orbit move at?
3070m/s
Describe 3 different types of orbits that artificial satellites can be put into.
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
What is a nebula?
a cloud of dust and gasses mainly hydrogen
How does a protostar form?
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
What is a fusion reaction?
when elements are forced due to high temperature and pressure to fuse together.
How is the main sequence star formed?
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.
In what stage is our sun in now?
is in the main sequence star part of its life cycle
For stars with similar sizes to our sun , how long are they stable for?
10billion years
What happens when all the hydrogen has been formed into helium?
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.
how long are red giants stable for?
a billion years
How is a white dwarf formed?
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.
What are the main differences between a normal life cycle of our sun and the life cycle of of a massive star?
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.
What are the two possible outcomes of a supernova and how is it decided which one is formed?
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
What is the doppler effect?
The doppler affect
How does red shift work?
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
How is the blue shift measured?
How is the red shift measured?
It is measured by how far along the spectrum the lines have moved
How is the blue shift measured?
It is measured by how far along the spectrum the lines have moved
How does red shift prove the universe is expanding?
What is the Big Bang theory?
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
What is the steady state theory?
What does the CMB stand for?
What is the CMB?
