There will be many occasions throughout your study of physics when you will need to draw graphs. This subsection gives some important guidelines for this activity.

1. Decide which is the independent variable and which the dependent variable. Plot the independent variable along the horizontal axis and the dependent variable along the vertical axis. This is purely a convention but is why, for instance, we usually plot the time
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We have all experienced that momentary feeling of lightness when an elevator begins its downward motion. It is almost as if our weight had suddenly been reduced or, conceivably, that the pull of the Earth's gravity had decreased for a moment. But imagine what it would be like if the lift cable had suddenly snapped and the lift, with you in it, had plummeted downward. Apart from stark terror, what else do you think you would experience during your fall? What would the physical experience
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Learning outcomes

After studying this unit you should be able to:

• explain the meaning of all the newly defined (emboldened) terms introduced in this unit;

• draw, analyse and interpret positionâ€“time, displacementâ€“time, velocityâ€“time and accelerationâ€“time graphs. Where appropriate, you should also be able to relate those graphs one to another and to the functions or equations that describe them, particularly in the case of straight-line graphs;

• find the derivati
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Acknowledgements

## Video Materials

This extract is taken from S809 Â© 2005 The Open University.

All written material contained within this unit originated at the Open University.

Author(s): The Open University

2.2.4 Film cassette and grid

As the X-rays pass through the patient some of them will be scattered and will therefore not follow the expected line through the patient. If these reach the detector they will blur the image. Some of the scattered radiation can be removed by a grid, usually oscillating, placed between the patient and the detector.

Analogue imaging systems use either film alone (rarely) or a combination of a film and fluorescent material (phosphor). The phosphor fluoresces and produces visible light whi
Author(s): The Open University

Acknowledgements

Except for third party materials and otherwise stated (see terms and conditions), this content is made available under a Creative Commons Attribution-NonCommercial-ShareAlike 2.0 Licence

The following appears in Introduction to Astrobiology (Planetary Science Book 2: ISBN 0-521-54621-4) which is published in ass
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2.3 Examining Europa's surface

It is all very well speculating about conditions in an ocean below Europa's ice, but what evidence is there that it actually exists? After all, tidal heating might not result in ice melting on a global scale, and current geophysical models of Europa's internal structure (e.g. Figure 14 in Section 1.5) cannot te
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Acknowledgements

The content acknowledged below is Proprietary (see terms and conditions) and is used under licence. This content is made available under a Creative Commons Attribution-NonCommercial-ShareAlike 2.0 Licence

Grateful acknowledgement is made to the following sources for permission to reproduce material in this unit:

T
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2 Who are the anthropoids?

As you know, the suborder Anthropoidea includes monkeys, apes and humans. You will be aware from reading LoM that taxonomists group monkeys according to the shape of their nose: Old World monkeys are catarrhines and New World monkeys are platyrrhines [p. 264]. In fact, apes and humans share many traits with Old World monkeys, so they too belong to the catarrhrines, whereas the New World monkeys are sufficiently distinct to be contained within a grouping of their own. DA also mentions other an
Author(s): The Open University

6 Promoting science promotion: the move from deficit to dialogue

This unit has tried to distinguish between institutional science outreach events and independent alternatives by recognising some of their characteristics and evaluating the extent to which they fulfil (and even create) a political mandate for PEST (Public Engagement in Science and Technology). Although institutional events sometimes involve the deficit style of â€˜top-downâ€™ transmission of facts, the examples provided in this unit suggest that they are increasingly imaginative and unusual.
Author(s): The Open University

2.3 ‘Go Say’ science promotion events

An increasing number of science museums and science centres hold regular organised events that stand apart from their exhibitions. The Dana Centre, which now has a permanent venue in the Wellcome Wolfson Building at the Science Museum, holds 10â€“20 events each month. They are designed to provoke discussion through a blend of debate, art, multimedia and performance, covering issues such as the ethics of prolonging the life of foetuses, the role of science in alleviating poverty, and what is,
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4.1 Introduction

Domestication of dogs and of most other livestock took place so long ago that reconstructing the course of events is extremely difficult. Written records and illustrations describing the origins of many modern breeds are also sparse until the 19th century. We can only guess at what the domesticators were aiming to produce and how and when domesticated traits appeared in the species subjected to artificial selection. However, a little-known experiment on the domestication of red foxes (Vulp
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3.2 Angular size, actual size and distance

The angular size of an object is determined uniquely by its actual size and its distance from the observer. For an object of fixed size, the larger the distance, the smaller the angular size. For objects at a fixed distance, the larger the actual size of an object, the larger its angular size. For objects with small angular sizes, such as typical astronomical objects, the precise relationship between angular size, actual size and distance is well approximated by th
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1.3 Beyond visible light

During the twentieth century, astronomers extended their capabilities by developing telescopes and detectors that were sensitive to radio waves, microwaves, infrared and ultraviolet radiation, X-rays and gamma rays. All these forms of electromagnetic radiation, along with visible light, are emitted by the Sun.

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6 Reflection

Most of the activities that you have done so far are based on your understanding of single sections that you have just read. Activity 8 which follows, is different. It requires you to assemble and integrate information over the whole â€˜Life in the treesâ€™ topic and is likely to require some extra effort and thought. Integrating information from different sections of the unit; is an important element in building your study skills. You're asked here to assemble evidence in support of a partic
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5.1 Introduction

The island of Madagascar is relatively small compared to the enormous landmasses of Africa, Asia and South America inhabited by the primates I've mentioned up to now. Yet of the 250 or so living primate species, more than 30 species of lemur live in Madagascar â€“ an astonishingly high 13 per cent or so of all primate species. Their diversity is reflected in the identification of no fewer than five families, related in the way suggested in Author(s): The Open University

2.3 The colugo

In LoM, DA vividly describes one particular evolutionary development associated with tree dwelling â€“ taking to the air [pp. 221â€“227]. The gliding habit evolved independently in different mammalian lineages and yet the anatomical modifications that allow it are similar in, for example, flying squirrels and the unrelated colugo. In particular, the â€˜sail of skinâ€™ [p. 221], technically termed a patagium, stretches between the limbs â€“ and a good deal further in the colugo, acting as an e
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7 The threat of extinction

DA ends his book by writing eloquently of the dangers of extinction faced by mammals, from habitat loss as we exploit our environment to produce more and more food, for our growing population. However bleak the picture, there is still time and opportunity to save mammal species from extinction. Although bison in the USA and Canada were reduced to barely 1000 individuals in 1900, their numbers have now risen to well over 150 000 thanks to the efforts of First Nation indigenous peoples, and ran
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2.2 Energy flow in ecosystems

You are about to meet some very large numbers, expressed in scientific notation, and some new units. The new units are those that are used to measure the amount of solar energy received by a part of the Earth's surface. Since plants are dependent on light for photosynthesis, the amount of plant material that ca
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10 Living in herds

Wildebeest are only one of the species of plant predator that live in herds. Many others do too.

## Activity 7

Watch the the TV programme from 30.48â€“47.32 and read LoM p. 109. Identify and write down (a) a couple of advantages and
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