- Explain what has to happen for the passage of time to be measured, giving an example
Something has to change for the passage of time to be measured
e.g. the apparent position of the sun in the sky.
- Explain what is meant by the “arrow of time”.
Time only moves forward, not backwards. This is because the universe naturally moves from a state of order to disorder and not the reverse.
- Define entropy, giving an example.
Entropy is a measure of disorder,
e.g. a sandcastle has low entropy because it is ordered; (less ways it could be arranged)
a pile of sand has high entropy because it is disordered. (lots of ways it could be arranged)
- How is the entropy of the universe changing over time?
The universe is moving from low entropy (order) to high entropy (disorder).
- State the approximate age of the universe.
The approximate age of the universe is 13.8 billion years.
- Perform calculations using scientific notation.
Example: What is 13.8 billion years in scientific notation?
13.8 billion years = 13,800,000,000 years = 1.38 x 1010 years
- Perform calculations using scientific notation.
Example: Convert 3.00 x 108 m/s into normal notation.
3.00 x 108 m/s = 300,000,000 m/s
- State the speed of light in m/s and its symbol.
The speed of light (c) is 3.00 x 108 m/s (or 300,000,000 m/s)
- State what is important about the speed of light.
The speed of light is the greatest speed achievable in the universe.
- State what the symbols mean and what units are used for
v=d/t
or
d = vt
d - distance (m)
v - speed (m/s)
t - time (s)
- Example
At the 2008 Beijing Olympics, Usain Bolt ran 100m in 9.69 seconds. Calculate his average speed.
d = 100 m
t = 9.69 s
v = ?
v = d/t
= 100/9.69
v = 10.32 m/s
- Example
You run at a steady speed of 6 m/s for 5 minutes. How far did you go?
v = 6 m/s
t = 5 min = 5 x 60 = 300 s
d = ?
d = vt
= 6x300
d = 1,800 m
- Example
James send a bowling ball off at 8.81 m/s. The first pin is 18.29 m away.
How long does it take for the bowl to hit the pin?
v = 8.81 m/s
d = 18.29 m
t = ?
d = vt
- 29 = 8.81xt
- 81xt = 18.29
t = 18.29/8.81
t = 2.08 s
- Example (involving light)
Light takes 1.28 seconds to travel from the moon to the earth. How far away is the moon?
v = c = 3 x 108 m/s
t = 1.28 s
d = ?
d = vt
= 3 x 108 x 1.28
d = 3.84 x 108 m
- Example (invloving light)
The sun is 1.5 x 1011 m away.
How long does it take light to travel from the sun to the Earth?
v = c = 3 x 108 m/s
d = 1.5 x 1011 m
t = ?
d = vt
1.5 x 1011 = 3 x 108 x t
3 x 108 x t = 1.5 x 1011
t = 1.5 x 1011/3 x 108
t = 500 s
- Explain how viewing the stars is looking back in time.
The stars are so far away that light will take many years to reach us from them. This means the light we see now left the stars many years ago and we see what the stars looked like at that time.
- State what is meant by a light year.
A light year is the distance that light travels in one year.
- State what Monsignor Georges Lemaître is famous for.
Monsignor Georges Lemaître was the first to siggest that the universe is expanding.
- State what scientific discovery Edwin Hubble is famous for.
Edwin Hubble obtained experimental proof of the expanding universe.
- Describe what Hubble’s Law tells us.
Hubble’s Law tells us that the further away a galaxy, the faster its recessional speed (how fast it is moving away from us).
- Give a simple account of the Big Bang.
The Big Bang is the name given to the start of the universe, when the universe expanded rapidly from a single point.
- State what particles were first to form after the Big Bang.
The first particles to form after the Big bang were quarks.
- Name the six different types (flavours) of quark.
The six different types (flavours) of quark are Up, Down, Top, Bottom, Strange and Charm.
- State which three quarks combine to form a proton.
A proton consists of Up, Up, Down quarks.
