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**preview**shows half of the first page. to view the full**3 pages of the document.**Lecture 2 – January 7, 2015

Models in Science

- In general, a model is something that represents reality

- A scientific model is an idea that can be used to describe an aspect of reality and has

withstood observational or experimental tests

- We can also develop conceptual models to help us think about how nature works

Scale Model: The Solar System

- How do we setup a scale model?

oScale = actual size/desired scale size

- To resize the Sun so it fits in this room, the scale would be a factor of about 80,000

- If we compressed distances by the same factor, the planets would be well off-campus

oObservations

Rocky planets are close together than Jovian (gas planets)

Sizes of planets are puny compared to distances between them

The Astronomical Unit

- We can specify distances in the Solar System by comparing them to the average Earth-

Sun distance

- 1 AU = 150 000 000 km = 150 000 000 000 m

- A planet twice as far from the Sun would be 2 AU away

Scientific Notation

- Specifying how many zeroes a number has is known as scientific notation

o10 = 10^1

o100 = 10^2

o1000 = 10^3

o1 Googol = 10^100

- i.e. the Earth is on average 150 000 000 000 meters from the Sun

oWould be written as a coefficient between one and ten, multiple by the

appropriate power of 10

oAnswer: 1.5 x 10^11 meters

- To multiply two or more numbers written in scientific notation just;

oMultiply the coefficients

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