H5

H.5.1
The Muon Experiment:

Evidence: Muons are observed on the surface of the Earth.

Inference: Time dilation and Length contraction has taken place because the Muons would otherwise decay only after 1 kilometre.

H4

The Twin Paradox:
There are 2 identical twins named Anantha and Ahtnana.
Anantha sees Ahtnana's clock tick more slowly than her own, so he things that Ahtnana is ageing more slowly than Ahtnana is. Anantha therefore expects that when Ahtnana returns,Ahtnana will be the younger. 


Ahtnana sees Anantha's clock tick more slowly than her own so thinks a is aging more slowly. B therefore expects that Anantha will be younger when he returns.
The Paradox is that they cannot both be the younger one out of the two.


So who is actually the youngest?
Since Ahtnana had to accelerate when he started, when he turned around to come home, and when she stopped at the end. Ahtnana is therefore in a non-inertial frame of reference, so the problem can't be solved with special relativity. General Relativity shows that during acceleration, clocks also tick slowly so B will in fact be the younger out of the 2.


What was Developed to satisfy the Twin Paradox?
The General Theory of Relativity was invented and it satisfied the Paradox as the General Theory took non-inertial frames of reference into account and is able to deal with them.


Hafele-Keating Experiment:

Question 7,8 and 9:

H3

H 3.1


Light Clock:




Describe the observations either Jack and Jill or observer A and B:


Observer A and B both have light clocks that time 1 nanosecond for every time light reflects through a cycle.
But observer B is inside a glass carriage travelling at velocity v relative to observer A. Because the carriage is moving relative to observer A, the distance travelled is greater, but the speed of light is still c (the same in all inertial frames).
Therefore the time between the light leaving the lower surface and returning must now be greater than a nanosecond.


Define Light clock:


A light clock is a clock in which a pulse of light is sent and reflected off glass and returns to the point the pulse was given from.


Lorenz Factor Graph:

Relativity

Define a frame of reference: 
A frame of reference is a system of coordinates that enables the position of various objects to be specified.


Define Galilean transformation:
Galilean transformation are made under the assumptions that time measurement (and space measurements) are independent of the observer. 

G3 Questions:

a) A Galilean transformation are made under the assumptions that time measurement (and space measurements) are independent of the observer. 

b) i) 1.96c

G1 Questions:

a) 1.90c

E 6.4 - E 6.7

E 6.4
State Hubble's law
V = Ho d


E 6.5
Discuss the limitations of Hubble's law:
Hubble's law predicts that the recessional velocity of the galaxy will be Hx. the assumption is that the universe is travelling at this constant speed since the beginning of the Universe. However, the gravitational attraction between galaxies means that the speed of recession decreases cosntantly. The fact that we assume that the recession velocity is constant, is a limitation of Hubble's law. Also, the data points in the graph below are scattered around the trend line thus showing that there are quite big random errors in the measurements. 

E6

E 6.1
Describe the distribution of galaxies in the universe


Define the term galactic cluster:

• A cluster of roughly a few hundred young stars in a loose distribution. Also called an open cluster. Source: Encyclopaedia.com

Source: http://www.physicscentral.com/explore/action/images/abell-cluster.jpg

Define the term galactic super-cluster:

• Superclusters are large groups of smaller galaxy groups and clusters and are among the largest structures of the cosmos. Source: en.wikipedia.org/wiki/Galactic_supercluster

Source: http://www.dragonslain.com/large_clusters.gif

E6.2

Explain the red-shift of light from different galaxies

Why are galaxies that are the furthest away red-shifted the most? :

• Because the universe is constantly expanding the the galaxies which are on the outer part of the big bang are moving away from the centre the fastest.

12.3

Outline the reasons for power losses in transmission lines and real transformers

Resistance of a transformer result in the transformer heating up.

Eddy currents. The currents can be reduced by laminating the core into individually electrically insulated thin strips.

Hysteresis losses causes the iron core to warm up due to the continued cycle of changes to its magnetism.

Flux losses are caused by magnetic leakage. A transformer is only 100% efficient if all of the magnetic flux that is produced by the primary links with the secondary.

E 3.1 - E 3.8

E 3.1
Define the parsec


"A unit of astronomical length based on the distance from Earth at which stellar parallax is 1 second of arc; equivalent to 3.262 light years"


Source: wordnetweb.princeton.edu/perl/webwn

E5

Describe the conditions that initiate fusion in star:
Stars are formed when large clouds of gas and dust are compressed. The cannot form on their own because the gravitational force is not big enough to pull the particles together. A large supernova or a collision with another star will cause the process to occur.


State the effect of a star's mass on the end product of a nuclear fusion:

• A star will eventually start fusing helium and hydrogen will become rare.
  • Fusion reactions will then happen less often The core of the star will begin to collapse as the star is no longer in equilibrium.The collapse of the star increases its core temperature. Because of the higher pressure and temperature 
• • in the core helium fusion is now possible
  .

E 4.8 - E 4.10

Graph showing the 3 possible fates of the Universe:

Taken from Chris Hamper's Physics texbook for the IB

Definitions of the three possible fates:

• Open universe
• The density of the Universe is lower than the critical density therefore the universe continues to expand
• Flat universe
• The density of the Universe is exactly at the critical density therefore the universe ceases to expand or contract.
• Closed universe
• The density of the Universe is greater than the critical density, therefore the universe would contract and may in turn lead to a "Big-crunch".

Definition of Critical Density:

• The Critical Density is the exact density of the universe required for the fate of the universe to neither expand or contract (flat fate).

How does the density of the Universe relate to its fate in terms of the critical density?:

• The density of the Universe is the deciding factor when you consider its fate in the long run. We deduce the fate of the universe by comparing its density to the critical density. If the density of the Universe is over the critical density the the universe will contract and collapse into singularity. If the density of the universe is lower than the critical density then the universe will continue to expand. If the critical density and density of the universe are identical the universe will stop expanding and turn static. Although this is highly unlikely as the density of the universe has to match the critical density EXACTLY.