physics (s2 exam) Flashcards
earth in space test
what are all the planets in order?
mercury, venus, earth, mars, jupiter, saturn, uranus, neptune
(mvem jsun)
how many cycles of the moon are there in a single earth year?
13.4
what is a day?
the amount of time it takes for a planet to orbit on its own axes
(earth = 24 hours)
what is a year?
the amount of time it takes for a planet to orbit the sun
(earth = 365.25 days)
why, if a planet is further away from the sun, does it take longer to fully orbit?
because it has a larger distance to travel around the sun which causes a longer planet year (longer time)
what planet(s) have the longest/shortest earth days per year
shortest: venus earth year is 225 venus days (venus day = 243 earth days)
longest: jupiter 1 earth year = 12 earth years)
what is a month?
approximately the amount of time it takes the moon to orbit earth once
what is the light year formula?
300,000,000 x 365.25 x 24 x 60 x 60
= 9.5 x 10¹⁵m - {don’t forget units}
x whatever amount of light years needed
what is the life cycle of a star for the 𝗵𝗶𝗴𝗵 𝗺𝗮𝘀𝘀 𝘀𝘁𝗮𝗿?
- stellar nebulae
- high mass star
- red super giant
- super nova
- neutron star
- black hole (if 2.5+ solar masses)
what is the life cycle of a star for the 𝗹𝗼𝘄 𝗺𝗮𝘀𝘀 𝘀𝘁𝗮𝗿?
- stellar nebulae
- low mass star
- red giant
- planetary nebula
- white dwarf
- black dwarf
what does schwarzschild mean? (to do with black holes)
the point of no return (also known as event horizon)
what is a black hole?
- it has a large concentration of matter (packed density)
- crushes matter to inflate density
- it recycles space objects
- stabilizes the formation of the galaxy
- has to be over 2.5 solar masses or its a neutron star
what is a galaxy?
- our galaxy is the milky way (spiral galaxy)
- made up of dust, gas, billions of stars and their solar system
- galaxies are made out of 75% hydrogen, 25% helium
- universe has 27% dark matter
what are the 4 main types of galaxies?
- peculiar
- spiral
- elliptical
- irregular
(pesi)
what is red shift?
- measured using a spectroscope
- used to deduce how far/close objects are from space
- hubble’s law (the name of the observation of redshifting and how close/far objects are from space)
- proves the earth is still expanding
- it is light from galaxies which are redshifting when the galaxies are moving away from the earth
what is the big bang theory?
- the theory of the origin of the universe
- universe began at just a single point
- began to expand to become larger
- is still expanding
why is it warm for us in june?
the northern hemisphere is tilted towards the sun which gets more heat energy from the fun for longer (= longer days)
why is it cold for us in december?
the northern hemisphere is tilted away from the sun which means it gets less heat energy from the sun (= days are shorter)
why do we get well defined shadows when it’s a sunny day?
because the light can directly travel from the sun
why do shadows get shorter as the day progresses (mid-day)?
the sun rises in the sky meaning it becomes more directly overhead which causes it to go straight down making the shadow less visible or disappear
what happens to shadows as the sun begins to set?
shadows slowly become longer (sun angle)
how does light travel?
in straight lines
when is the sun higher/lower, winter/summer?
summer : higher
winter : lower
what is the closest star to us?
proxima centauri - 2.28 light years away
