Space - Red Shift + Big Bang + Gravity + Orbits

Question 1

What are 6 things that are in our solar system?

Answer 1

• planets
• Dwarf planets
• Moons
• Artificial Satellites
• Asteroids
• Comets

Question 2

whats the different between a steroid and a comet

Answer 2

Asteroid:
- lumps of rock + metal that orbit the Sun
- usually found in the asteroid belt
Comets:
- lumps of ice + dust
- highly elliptical - some travel from near to the Sun to outskirts of our solar system

Question 3

If object is travelling in a circle, is it constantly changing direction and accelerating

Answer 3

Yes

Question 4

what is centripetal force

Answer 4

• the force of gravity of the planet from the Sun
• force acting towards centre o the circle

Question 5

explain how planets are constantly in a circular orbit

Answer 5

• planets travel around in Sun in *almost circular orbits**
• objects in a circular orbits travel at constant speed but constant changing direction –> changing velocity –> constantly accelerating
• resultant force needed to cause acceleration:
• resultant force = gravity and acts at 90 degrees to instantaneous velocity (velocity of object) of object –> keeps it travelling in a circle
• Sun/Earth gravitational pull can only slightly change orbiting planets direction as they planet has a lot of momentum at 90 degrees compared to gravity.

Question 6

what 2 factors result in a steady orbit.

Answer 6

• instantaneous velocity of object
• gravitational pull larger object

Question 7

what is the relationship between the size of a planets orbit and its speed

Answer 7

Smaller orbit
- greater gravitational force –> closer to the larger planet
- in order to stary in orbit, smaller planet needs increase instantaneous velocity to travel faster –> balance gravity
- allow to maintain stable orbit and not be pulled into centre

Question 8

explain red shift

Answer 8

• absorption spectra shows visible light from Sun shows red = longer wavelength and purple = shorter wavelength
• Suns atmosphere contain lots of different chemicals and some absorb certain wavelengths of light
• when light reaches Earth certain wavelengths absorbed –> pattern ofblack lines on spectrum
• light from distance galaxies have a same pattern of black lines but all shifted towards red end of spectrum –> red shift

Question 9

what does red shift evidence for

Answer 9

distant galaxies are moving away from earth, as waves travelling towards us have longer wavelengths

Question 10

what is the relationship between the distance of a galaxy and they speed at which it moves in

Answer 10

• greater the distance in galaxies = greater the speed at which its moves away from Earth

Question 11

if a there is a large red-shift what does it imply about the distance of the galacy

Answer 11

larger distance

Question 12

how does Cosmic Microwave Background provide another possible explanation for the Big Bang

Answer 12

• scientists can detect low frequency microwave radiation coming from all directions and all parts of the universe
• CMBR was created as high-energy gamma radiation just after the big bang
• as universe expanded –> wavelength of gamma was stretched into longer wavelengths –> now is microwave radiation
• CMBR might be leftover energy from initial explosion

Question 13

what is dark matter and dark energy

Answer 13

Dark Matter
- missing mass/ empty space
- cannot be seen, adds density to the universe
1, if density less than particular amount –> expand forever –> Big Yawn
2. if density more than a particular amount –> stop expanding and reverse –> Big Crunch
Dark Energy
- unknown source of energy, must be causing this accelerating motion