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Physics > P16: Space > Flashcards

P16: Space Flashcards

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1
Q

eg of rocky planets and gas planets?

A

rocky: Mercury, Venus, Earth, Mars
gas : Jupiter, Satrn Uranus, Neptune

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2
Q

eg of natural satellites/artificial satellites?

A

NATURAL :the moon
ARTIFICIAL : International Space station

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3
Q

difference between comets and asteroids?

A

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

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4
Q

formation of the sun

A
  1. cloud of dust and gas - nebula
    - gravity pulled this cloud together into ball
  2. nebula collapsed - centre of ball becomes dense/hot (rotates)
  3. nuclear fusion began –> forms protostar (our sun)
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5
Q

what is meant by the equilibrium of stars?

A

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

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6
Q

how does nuclear fusion form new elements/ how is helium formed ?

A

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

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7
Q

how are elements heavier than iron formed?

A

produced in supernovae explosions
- releases alot of energy/neutrons
- elements produced by fusion combine with neutrons to form heavier elements

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8
Q

formation of stars?

A
  1. Nebula- gaint cloud of hydrogen gas/dust
  2. 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
  3. 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
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9
Q

how do stars like our sun die?

A
    • hydrogen runs out so fusion reactions run out
      - core shrinks and heats up (inward gravity greater than outward pressure)
  2. more reactions occur (helium nuclei form beryllium nuclei) - cause outer part of star to EXPAND - RED GAINT
  3. star will become unstable - ejects layer of dust/gas called PLANETARY NEBULA
  4. core left behind is called WHITE DWARF/ collapses
  5. becomes black dwarf when lost alot of energy
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10
Q

death of massive star?

A
    • hydrogen runs out so fusion reactions run out
      - core shrinks and heats up (inward gravity greater than outward pressure)
  2. more reactions occur (helium nuclei form beryllium nuclei) - cause outer part of star to EXPAND - RED SUPPER GAINT
  3. SUPERNOVA - once all reactions finished - core collapses suddenly causing SUPERNOVA - ejects planetary nebula / leaves neutron star
  4. neutron star collapses under gravity –> BLACK HOLE
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11
Q

why does an object accelerate when orbiting in circular motion?

A

circular path means changing direction
- changing direction causes changing velocity
- acceleration is rate of change of velocity so is accelerating

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12
Q

what force causes circular motion?

A

a resultant force is needed to cause acceleration
- gravity acts at right angles to the instantaneous velocity

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13
Q

similarities and differences of the orbits of planets around sun?

A

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

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14
Q

what happens if moons are closer to the planet?

A

The shorter the time it will take to orbit
The greater the speed in the orbit

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15
Q

what happens if speed of satellite is too big or too small?

A

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

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16
Q

how to mainatin stable orbit?

A

If the speed increases the radius must increase
If the speed decreases the radius must decrease

17
Q

how is a stable orbit for a comet formed?

A
  • 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
18
Q

what is the doppler effect?

A
  • moving object will cause wavelength of waves infront of source to decrease / frenquency increase
  • behind object wavelength of waves increases/ frequency decreases
19
Q

what is the red shift/ blue shift ?

A

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

20
Q

what is evidence for an expanding universe ?

A
  • 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
21
Q

what happens if a galaxy’s speed increase/ decreases?

A

INCREASES : moves further
DESCREASE : move the least

22
Q

what is dark energy

A

unseen matter in the universe

23
Q

what is the universe and what are the main ideas of the big bang theory?

A

collection of galaxies
- universe started out at a single/small point
- and exploded/expanded outwards

24
Q

why does nuclar fusion release energy?

A

mass of bigger nuclei is smaller than mass of smaller nuclei combined
- this mass difference is released as energy

Physics (11 decks)

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