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S2 Physics > Cosmology > Flashcards

Cosmology Flashcards

1
Q

What is the time measured by?

A

The passage of time is measured by something changing

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2
Q

What is the universe currently moving from?

A

The universe naturally moves from a state of order to disorder

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3
Q

What is the process of the universe moving from order to disorder called?

A

The arrow of time

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4
Q

What is entropy?

A

Entropy is the measure of disorder in a system

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5
Q

In a pile of sand is there high or low entropy?

A

High as there is no order

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6
Q

When someone makes a sand castle is there high or low entropy?

A

Low as someone put order into the system

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7
Q

What is the arrow of time?

A

The arrow of time is the change from past to future, time always moves from past to future

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8
Q

What is the approximate age of the universe?

A

13.8 billion years old

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9
Q

What is the approximate age of the universe in scientific notation?

A

1.37 x 10^10

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10
Q

What is the speed of light?

A

The speed of light is the greatest achievable speed in our universe!

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11
Q

What is the symbol for the speed of light?

A

‘C’

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12
Q

What is the equation to find out the average speed of a journey?

A

Speed= Distance/Time
Or…
*v=d/t
*v= velocity

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13
Q

What is the speed of light in scientific notation?

A

3 x 10^8

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14
Q

How does an oscilloscope measure the speed of light?

A

The beam of light is sent out from the transmitter causing a peak on the oscilloscope, the light beam travels in a straight line to the mirror and reflects off it travelling back in a straight line to the receiver which is detected by the oscilloscope causing a second peak telling us the time measure (time). A measuring tape is used to measure the total round trip (distance) of the and we can use the equation v=d/t to calculate the speed.
MAKE SURE D IS X2

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15
Q

When we look at the stars how are we looking back in time?

A

The light we are looking at left the stars billions of light years ago meaning we are looking back in time

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16
Q

What is a light year?

A

A light year is how far light travels in a year, it is a measure of DISTANCE!

17
Q

What was George Lemaîtres theory about the universe?

A

Lemaître was the first to suggest that the universe is expanding, he didn’t have any proof but his theory led to the big bang

18
Q

What did Edwin Hubble do that led to Lemaîtres theory being true?

A

Hubble discovered objects far too far way to be in the Milky Way, he found other galaxies beyond our own. He also gained experimental proof that these galaxies were all moving away from each other, the universe was indeed expanding!

19
Q

Explain Hubbles law

A

All galaxies are receding from each other, they each have a recessional speed. The further away a Galaxy is, the greater is recessional speed. All galaxies are moving away from each other meaning the universe must be expanding

20
Q

Give a simple account of the Big Bang

A
  1. The Big Bang 💥 (0)
    2.Tiny particles called quarks form (10^-6 seconds)
  2. The universe has cooled enough for particles like proton and neutrons to form (1 second)
  3. Further cooling allowed other electrons to form (1-10 seconds)
  4. Light appears 💡 (10 seconds)
  5. Temperature has fallen enough for Hydrogen and Helium to form (3-20 minutes)
  6. Stars being to form (150 million years)
  7. Solar system forms (8 billion years)
  8. Earth forms 🌍 (9 billion years)
  9. Today all galaxies are still moving apart (13.8 billion years)
21
Q

What were the first particles to form after the Big Bang?

A

Quarks

22
Q

What are the 6 flavour of quarks?

A

Up (U), down (D), top (T), bottom (B), strange (S), charm (C)

23
Q

Which three quarks form a proton?

A

Two Ups and a down= U U
D

24
Q

Which three quarks form a neutron?

A

Two downs and an up= D D
U

25
Q

What charge does a proton have?

A

Positive

26
Q

What charge does a neutron have?

A

Neutral

27
Q

What is an atom of an element?

A

An atom of hydrogen consists of one proton (the nucleus) and one electron which orbits the nucleus

28
Q

What is the nucleus of an element?

A

The nucleus of a hydrogen atom is simply a proton which carries a +1 electron charge

29
Q

What is an element?

A

An element is a substance that contains only one type of atom. E.g. the element hydrogen only contains hydrogen atoms

30
Q

What is nuclear notation?

A

Nuclear notation is the way in which elements are represented
Ex/ Hydogen = 1
H
1

31
Q

What is the mass number in nuclear notation?

A

The mass number is the number on top of the elects symbol. This is the total number of protons and neutrons in the nucleus

32
Q

What is the atomic number in nuclear notation?

A

The atomic number is the number below the element symbols. This is the number of protons in the nucleus

S2 Physics (3 decks)

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