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8 Astrophysics – Part A “Units”

Aims…

8.1 use the following units: kilogram (kg), metre (m), metre/second (m/s),
metre/ second2 (m/s2), newton (N), second (s), newton/kilogram (N/kg)

General Ideas…

physical quantity is something that can be measured. For any measurement, the unit being used must be stated to give an understanding of the scale of the measurement.

For example, distance can be measured in kilometres or in miles. They are similar, but not the same and it is important to identify which was used for the measurement, to know how far the distance actually is.

Système Internationale d’Unités

The units that scientists use all over the world are standardised in the Système Internationale d’Unités – SI units. It is important to remember these six fundamental (or ‘base’) units of measurement:

There are many quantities scientists measure that come from the base units. These derived units are very useful to quote as measurements, but they are not fundamental as they come from fundamental units.

For example, frequency is the number of times something happens per unit of time.

NameUnitAbbreviation
FrequencyhertzHz
ForcenewtonN
EnergyjouleJ
PowerwattW
PressurepascalPa
Electric chargecoulombC
Work Done or WorkNm or JW
Gravity or accelerationNkg-1ms-2g or a
Momentumkgms-1p

Resources…

Use this powerpoint for a quick review…  8 Astrophysics Part A Units

Permanent link to this article: https://www.animatedscience.co.uk/igcse-physics-introduction-and-resources/8-astrophysics-part-a-units

8 Astrophysics – Part B “Orbits”

Syllabus Aims…
8.2 know that:

the universe is a large collection of billions of galaxies
a galaxy is a large collection of billions of stars
our solar system is in the Milky Way galaxy.

8.3 understand why gravitational field strength, g, and know that it is different on other planets and the Moon from that on the Earth
8.4 explain that …

8 Astrophysics – Part C “Stellar Evolution”

Aims…
8.7 understand how stars can be classified according to their colour
8.8 know that a star’s colour is related to its surface temperature
8.9 describe the evolution of stars of similar mass to the Sun through the following stages:

Nebula
Star (main sequence)
Red giant
White dwarf

8.10 describe the evolution of stars with a mass larger than the Sun
Triple Only…. 
8.11P understand …

8 Astrophysics – Part D “Cosmology”

Aims… (Triple Only)
8.13P describe the past evolution of the universe and the main arguments in favour of the Big Bang
8.14P describe evidence that supports the Big Bang theory (red-shift and cosmic microwave background (CMB) radiation)
8.15P describe that if a wave source is moving relative to an observer there will be a change in the observed …

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