P1 (Physics): The Earth in the Universe

This section shows links to revision materials Physics P1 - The Earth in the Universe

Overview of Module

Scientific discoveries in the solar system and beyond continue to inspire popular culture and affect

our understanding of our place in the Universe. In this module, candidates explore the scale of the

Universe and its past, present and future, and consider the ideas scientists have and their evidence for

them.

Closer to home, candidates consider long-term and short-term changes in the Earth’s crust, and how

these changes impact on human life. In particular, they find out about earthquakes and volcanoes –

explaining them, predicting them and coping with them.

The module focuses on how we know the things we think we know about the Earth and its place in

the Universe. Across the whole module, candidates encounter many examples showing relationships

between data and explanations. Through these contexts they learn about the way scientists

communicate and develop new explanations.

Physics

P1 - The Earth in the Universe (click on the links below for general headings or look below for more detail on what you may be tested on)

• Earth, stars, galaxies and space,
• How the Earth is changing
• Seismic Waves

P1.1 What do we know about the place of the Earth in the Universe?

1. recall that the Earth is one of eight planets moving in almost circular paths round the Sun which, together with other smaller objects orbiting the Sun (asteroids, dwarf planets, comets) and moons orbiting several planets, make up the solar system

2. describe the principal differences between planets, moons, the Sun, comets and asteroids 

including their relative sizes and motions

3. understand that the solar system was formed over very long periods from clouds of gases and dust in space, about five thousand million years ago

4. recall that the Sun is one of thousands of millions of stars in the Milky Way galaxy

5. recall that there are thousands of millions of galaxies, each containing thousands of millions of 

stars, and that all of these galaxies make up the Universe

6. put in order and recall the relative sizes of: the diameters of the Earth, the Sun, the Earth’s orbit, the solar system, the Milky Way, the distance from the Sun to the nearest star, and the distance from the Milky Way to the nearest galaxy

7. understand that all the evidence we have about distant stars and galaxies comes from the radiation astronomers can detect

8. recall that light travels through space (a vacuum) at a very high but finite speed, 300 000 km/s

9. recall that a light-year is the distance travelled by light in a year

10. understand that the finite speed of light means that very distant objects are observed as they were in the past, when the light we now see left them

11. understand how the distance to a star can be measured using parallax (qualitative idea only)

12. understand how the distance to a star can be estimated from its relative brightness

13. understand that light pollution and other atmospheric conditions interfere with observations of the night sky

14. explain why there are uncertainties about the distances of stars and galaxies with reference to the nature and difficulty of the observations on which these are based and the assumptions made in interpreting them

15. understand that the source of the Sun’s energy is the fusion of hydrogen nuclei

16. understand that all chemical elements with atoms heavier than helium were made in stars

17. understand that the redshift in the light coming from them suggests that distant galaxies are moving away from us

18. understand that (in general) the further away a galaxy is, the faster it is moving away from us

19. understand how the motions of galaxies suggests that space itself is expanding

20. recall and put in order the relative ages of the Earth, the Sun, and the Universe

21. recall that scientists believe the Universe began with a ‘big bang’ about 14 thousand million years ago

22. understand that the ultimate fate of the Universe is difficult to predict because of difficulties in measuring the very large distances involved and the mass of the Universe, and studying the motion of very distant objects.

P1.2 What do we know about the Earth and how it is changing?

1. understand how rocks provide evidence for changes in the Earth (erosion and sedimentation, 

fossils, folding)

2. understand that continents would be worn down to sea level by erosion, if mountains were not being continuously formed

3. understand that the rock processes seen today can account for past changes

4. understand that the age of the Earth can be estimated from, and must be greater than, the age of its oldest rocks, which are about four thousand million years old

5. understand Wegener’s theory of continental drift and his evidence for it (geometric fit of continents and their matching fossils and rock layers)

6. understand how Wegener’s theory accounts for mountain building

7. understand reasons for the rejection of Wegener’s theory by geologists of his time (movement of continents not detectable, too big an idea from limited evidence, simpler explanations of the same evidence, Wegener an outsider to the community of geologists)

8. understand that seafloor spreading is a consequence of movement of the mantle (convection due to heating by the core)

9. recall that seafloors spread by a few centimetres a year

10. understand how seafloor spreading and the periodic reversals of the Earth’s magnetic field can explain the pattern in the magnetisation of seafloor rocks on either side of the oceanic ridges

11. understand that earthquakes, volcanoes and mountain building generally occur at the edges of tectonic plates

12. understand how the movement of tectonic plates causes earthquakes, volcanoes and mountain building, and contributes to the rock cycle

13. recall that earthquakes produce wave motions on the surface and inside the Earth which can be detected by instruments located on the Earth’s surface

14. recall that earthquakes produce:

• a. P-waves (longitudinal waves) which travel through solids and liquids
• b. S-waves (transverse waves) which travel through solids but not liquids

15. describe the difference between a transverse and longitudinal wave

16. understand how differences in the wave speeds and behaviour of P-waves and S-waves can 

be used to give evidence for the structure of the Earth

17. in relation to waves, use the equation: distance (metres, m) = wave speed (metres per second, m/s) × time (seconds, s)

18. draw and label a diagram of the Earth to show its crust, mantle and core

19. recall that a wave is a disturbance, caused by a vibrating source, that transfers energy in the direction that the wave travels, without transferring matter

 

20. recall that the frequency of waves, in hertz (Hz), is the number of waves each second that are made by the source, or that pass through any particular point

 

21. recall that the wavelength of waves is the distance between the corresponding points on two adjacent cycles

 

22. recall that the amplitude of a wave is the distance from the maximum displacement to the undisturbed position

 

23. draw and interpret diagrams showing the amplitude and the wavelength of waves

 

24. use the equation: wave speed (metres per second, m/s)  = frequency (hertz, Hz) × wavelength (metres, m)

 

25. understand that for a constant wave speed the wavelength of the wave is inversely proportional to the frequency.