P2 - Space Flashcards
1
Q
How was our solar system formed?
A
- sun was formed from a nebula filled together by gravitational attraction
- creating a protostar
- more material drew in to a main sequence
- energy released by nuclear fusion keeps core hot
- material not drawn in by sun remained in orbit and created planets and other objects
- sun is in main sequence, kept balanced by expanding fusion and gravity acting onwards
2
Q
Explain the life cycles of stars
A
- NEBULA cloud of dust and gas drawn together by gravity to form a PROTOSTAR and eventually MAIN SEQUENCE
- In main sequence, hydrogen fused together to create helium and, in large stars, lithium
- more mass is converted in to energy by fusion
- mass decreases so outward forces are larger than gravity
- star expands and cools to form a RED GIANT or SUPER RED GIANT
- as star cools and hydrogen fuel is used up, outward forces are reduced
- gravity causes star to collapse inwards (temperature increases again) fuses helium and lithium in WHITE DWARFS then eventually BLACK DWARFS
- largest stars explode in to a SUPERNOVA releasing energy and scattering matter in to space leaving a BLACK HOLE or NEUTRON STAR
3
Q
How are new elements created?
A
- before stars, only hydrogen
- fusion in stars creates new elements
- all stars , even smallest, fuse hydrogen in to helium
- bigger stats fuse helium in to lithium and other lightweight elements, up to and including iron
- during a supernova of biggest stars, the amount of energy released is so great that temperature and pressure increase enough to force nuclei together to create elements heavier than iron
4
Q
What is the difference between a natural and artificial satellite?
A
natural satellites (eg moons) orbit planets whereas artificial satellites are man made that orbit earth, used for TV and GPS all use gravity to maintain orbit
5
Q
Why do objects stay in orbit?
circular motion
A
- force (gravity) acting towards centre
- unbalanced force causes acceleration towards centre
- acceleration does not cause the object to change speed
- causes change in direction
- velocity changes but speed is same
- instantaneous velocity is perpendicular to centripetal force
6
Q
What creates a centripetal force?
A
force of gravity pulling an object in a curved path
7
Q
How does radius effect speed?
A
If speed changes, radius must also change
For a stable orbit, the greater the radius the slower the speed
8
Q
What is the Doppler effect?
A
- moves towards detector, squashed together, smaller wavelength
- moves away from detector, spread apart, longer wavelength
9
Q
What is red shift?
A
The further away an object (star/planet) is, the more red it appears as red is the longest visible light wavelength
10
Q
Explain how red-shift provides evidence for the big bang theory
A
- all galaxies are moving away from one another as they appear red to us
- so they must all start from one very small, hot, dense region
