P16: Space Flashcards
eg of rocky planets and gas planets?
rocky: Mercury, Venus, Earth, Mars
gas : Jupiter, Satrn Uranus, Neptune
eg of natural satellites/artificial satellites?
NATURAL :the moon
ARTIFICIAL : International Space station
difference between comets and asteroids?
asteroids are small rocky objects that orbit the sun (asteroid belt lies between Mars and Jupiter)
comets are made of dust and ice / orbit sun in a different orbit to planets
- when comets approach sun, ice melts forming comet tail
formation of the sun
- cloud of dust and gas - nebula
- gravity pulled this cloud together into ball - nebula collapsed - centre of ball becomes dense/hot (rotates)
- nuclear fusion began –> forms protostar (our sun)
what is meant by the equilibrium of stars?
When the inward pull of gravity and the outward pressure acting on the star are equal the star will be in equilibrium
- if temp of star increases, outward pressure will increase –> star expands
how does nuclear fusion form new elements/ how is helium formed ?
2 light nuclei collide at HIGH SPEED and join to create LARGER/HEAVIER NUCLEUS
- released energy in form of heat/light
e.g hydrogen nuclei fuse together to form helium nuclei
- as star runs out of hydrogen, other fusion reactions take place forming nuclei of other elements
how are elements heavier than iron formed?
produced in supernovae explosions
- releases alot of energy/neutrons
- elements produced by fusion combine with neutrons to form heavier elements
formation of stars?
- Nebula- gaint cloud of hydrogen gas/dust
- gravity pulls nebula particles closer together to form HOT BALL OF GAS - PROTOSTAR
- as particles are pulled close together - density of protostar increases - more frequent collisons so temp increases -
main sequence- when protostar is hot enough , nuclear fusion occurs in core (hydrogen nuclei forms helium nuclei) - release heat/light
- star is in equilibrium (stable) bc inward gravity=outward pressure
how do stars like our sun die?
- hydrogen runs out so fusion reactions run out
- core shrinks and heats up (inward gravity greater than outward pressure)
- hydrogen runs out so fusion reactions run out
- more reactions occur (helium nuclei form beryllium nuclei) - cause outer part of star to EXPAND - RED GAINT
- star will become unstable - ejects layer of dust/gas called PLANETARY NEBULA
- core left behind is called WHITE DWARF/ collapses
- becomes black dwarf when lost alot of energy
death of massive star?
- hydrogen runs out so fusion reactions run out
- core shrinks and heats up (inward gravity greater than outward pressure)
- hydrogen runs out so fusion reactions run out
- more reactions occur (helium nuclei form beryllium nuclei) - cause outer part of star to EXPAND - RED SUPPER GAINT
- SUPERNOVA - once all reactions finished - core collapses suddenly causing SUPERNOVA - ejects planetary nebula / leaves neutron star
- neutron star collapses under gravity –> BLACK HOLE
why does an object accelerate when orbiting in circular motion?
circular path means changing direction
- changing direction causes changing velocity
- acceleration is rate of change of velocity so is accelerating
what force causes circular motion?
a resultant force is needed to cause acceleration
- gravity acts at right angles to the instantaneous velocity
similarities and differences of the orbits of planets around sun?
simliarities : eptical orbit
- orbit in the same plane
- travel in same direction
DIFFERENCES: - different distances from sun
- different speeds
- take different amaounts of time to orbit sun
what happens if moons are closer to the planet?
The shorter the time it will take to orbit
The greater the speed in the orbit
what happens if speed of satellite is too big or too small?
BIG : The radius of the orbit will increase /the satellite will spiral into space - the gravitational attraction cannot provide enough force to keep it in orbit
SMALL : radius of the orbit will decrease and the satellite will move towards planet- gravitational attraction is too strong
how to mainatin stable orbit?
If the speed increases the radius must increase
If the speed decreases the radius must decrease
how is a stable orbit for a comet formed?
- As the comet approaches the Sun, it loses gravitational potential energy and gains kinetic energy- causes the comet to speed up
- This increase in speed causes a slingshot effect, and the body will be flung back out into space again
- moves away from the Sun - the body will slow down, finishing its orbit
what is the doppler effect?
- moving object will cause wavelength of waves infront of source to decrease / frenquency increase
- behind object wavelength of waves increases/ frequency decreases
what is the red shift/ blue shift ?
red shift : shift in the wavelength of light towards the red end of spectrum
- if object moves away from observer , wavelength of light increases (waves more spread out)
- move closer to red end of spectrum
blue shift: if object moves closer to observer, wavelength of light decreases (waves squash)
- moving closer to blue end of spectrum
what is evidence for an expanding universe ?
- light coming towards us is red shifted - shows galaxies are moving away from us
- shows universe is expanding
- the greater the distance to galaxy , greater the redshift - seen by supernovae
- the further it is from us, the faster it is moving
- meaning the galaxies must have been much closer in the past
what happens if a galaxy’s speed increase/ decreases?
INCREASES : moves further
DESCREASE : move the least
what is dark energy
unseen matter in the universe
what is the universe and what are the main ideas of the big bang theory?
collection of galaxies
- universe started out at a single/small point
- and exploded/expanded outwards
why does nuclar fusion release energy?
mass of bigger nuclei is smaller than mass of smaller nuclei combined
- this mass difference is released as energy