Earth's physical resources: renewable energy
As the world responds to climate change, we explore whether sustainable energy can satisfy our need for endless economic growth, without radical changes in the way we live. This album examines power sources which provide cleaner alternatives to fossil fuels, such as wind power, biomass, hydro power, wave and tidal power, solar and geothermal power. The nine video tracks introduce the different approaches adopted in Britain and across Europe, the challenges faced and the projects of the future. T
Ecosystems: modelling the Earth
How can numerical models help us to understand our planet? How do we make sure they represent reality? This album introduces ongoing work to model the entire planet's ecosystems, simulating the complex physical, chemical and biological interactions taking place between every living organism and climatic activity. Since everything is interconnected, Earth systems modelling can help our understanding of how the Earth's processes affect each other. For example, by increasing the rate of decay of le
Migration
Migration is a free course looking at the migrations of animals, with special reference to birds, and also introducing the themes of movement, selection and homeostasis.
First published on Tue, 24 Jan 2017 as Migration. To find out more visit The Open University's
An introduction to energy resources Understanding energy resources involves considering all types of energy source from various sci
7.4 Models of active galaxies The standard model of an AGN consists of an accreting supermassive black hole (the engine) surrounded by a broad-line region contained within a torus of infrared emitting dust and a narrow-line region. Unified models attempt to explain the range of AGNs on the assumption that they differ only in luminosity and the angle at which they are viewed. One type of model attempts to unify radio-quiet AGNs. Type 1 Seyferts and type
4.2 Iron transport It is obvious that iron must be transported around the human body. Firstly, it must be transported from the food in the gut to the places where it is required. Mostly, iron is required in the bone marrow, where red blood cells are formed. Red blood cells have a finite lifetime of about only four months, and old cells are destroyed, usually in the spleen. Iron from the destruction of these cells is then transported from the spleen back to the bone marrow to be recycled. Iron cannot be tr
Introduction This unit provides an introduction to the evolution of mammals. We will be considering Darwin's observations on a great many mammals, and how he noticed that species fell into natural groups. We take as an example the evolution of one particularly interesting mammal, the whale, and look at evidence both from fossils and from DNA to see which other mammals are most closely related to whales. We see how the evidence from these two very different sources points to the same relationship and
Acknowledgements Grateful acknowledgement is made to the following sources for permission to reproduce material in this course: Couse image: Mike in Flickr made available under Creative Commons Attribution-NonCommercial-ShareAlike 2.0 Licence. The content acknowledg
References Acknowledgements The content acknowledged below is Proprietary (see terms and conditions). This content is made available under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 Licence Grateful acknowledgement is made to the following sources for permission to reproduce material in thi 1 The omnivores As you work through this course you will come across boxes, like this one, which give you advice about the study skills that you will be developing as you progress through the course. To avoid breaking up the flow of the text, they will usually appear at the start or end of the sections. As well as th 1 Observing the Moon Try to make out features on the surface of the Moon, even if you have no optical aid available. If you have the use of a pair of binoculars y Faraday and Maxwell 2.2.2 Energy and conservation Newtonian mechanics is concerned with explaining motion, yet it contains within it the much simpler idea that some things never change. Take the concept of mass, for example, which appears throughout Newtonian mechanics, including the law of gravitation. In Newtonian mechanics, mass is conserved. This means that the mass of the Universe is constant and the mass of any specified collection of particles is constant, no matter how much rearrangement occurs within the system. A chemist might take 6.5 Summary of Section 6 Growth cones respond to proximal and distal cues. The proximal cues in the extracellular matrix or other cells affect adhesion and result in chemotactic guidance. Distal cues are also in the extracellular matrix but they diffuse through it and result in the growth cone either moving towards the source (attractants) or away from it (repellants). These distal cues are chemotropic cues and can have different effects on different growth cones; what may be an attractant to one growth cone may be r 2.3.2 Salinity, desiccation and biotic interactions on seashores Tidal movements ensure that sea-shore habitats are, if not covered by seawater for part of each day, at least subject to spray-borne salt and wind. So, even well above the level of high tides, sea-shore organisms need to be more tolerant of salt than most terrestrial organisms. However, salinity (the concentration of salts dissolved in water) is not the only factor affecting sea-shore species. Seaweeds and shelled animals like limpets and barnacles are adapted to living in a highly saline mar 2.1 Introduction Ecology is usually defined as the study of organisms in their environments. In its broadest sense this definition includes the way we, the human species (Homo sapiens), interact with and use the environment. However, in 4.4.1 Tidal Energy The energy that causes the slow but regular rise and fall of the tides around our coastlines is not the same as that which creates waves. It is caused principally by the gravitational pull of the moon on the world's oceans. The sun also plays a minor role, not through its radiant energy but in the form of its gravitational pull, which exerts a small additional effect on tidal rhythms. The principal technology for harnessing tidal energy essentially involves building a low dam, or barrag 2 Altering the environment Later in this unit we will be considering a number of ways in which humans alter their environment. In what ways do you think we are altering the environment? 2.7 Cabling A distinction must be made between the optical fibre – a single strand of glass fibre – and the optical-fibre cable consisting of one or more strands of fibre and various protective coverings. Bare optical fibre is fragile and vulnerable, and the cabling must provide the properties given below.
Tensile strength: The cable should prevent the fibre being strained when the cable is under tension. When the cable is being laid, for exampl
Activity 1
Michael Faraday (1791-1867)
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Question 3
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