If a solid rectangular bar is excited by striking it, energy is supplied that starts the bar vibrating transversely. The bar will vibrate in a number of modes simultaneously since the striking action supplies energy over a range of frequencies. The motion of the bar will be the superposition of the standing-wave patterns of the excited modes.

Assume for the moment that the rectangular bar is supported in such a way that both ends are free to vibrate and the effects of the supports can b
Author(s): The Open University

If standing waves are set up when two travelling waves moving in opposite directions interact, then how are standing waves set up on a string and why are they set up only at certain frequencies?

To help answer these questions, I want you first to imagine a length of string that is fixed at one end and held in someone's hand at the other. Suppose the person holding the string flicks their end of the string in such a way that an upward pulse is sent along the string.

As the pulse pa
Author(s): The Open University

You learned earlier that when a musician plays a note on an instrument, they supply it with energy that causes the primary vibrator to oscillate at certain specific frequencies. In Section 5 we are going to look at what determines these specific frequencies for some of the primary vibrators found in different instruments.

In Unit TA212_1 Sound for music technology: an introduction, we talk about travelling waves: that is, waves that propagate outwards away from their sourc
Author(s): The Open University

For a player to be able to sound a musical instrument, there must be a means of inputting energy to set up the vibration. This energy may be introduced in a short, sharp burst or continuously over a period of time.

In the case of brass instruments such as the trumpet and trombone, and woodwind instruments such as the flute and oboe, the player feeds in energy by blowing air into the instrument. The energy can be supplied in a short burst â€“ in which case short-lived â€˜staccatoâ€™ note
Author(s): The Open University

Most of the major cities and harbours in the world are located on estuaries. The estuarine ecosystem is a unique intermediate between the sea, the land and fresh water.

A rather precise definition of an estuary is 'a semi-enclosed coastal body of water, which has a free connection with the open sea, and within which sea water is measurably diluted with fresh water derived from land drainage'. This excludes large bays with little or no freshwater flow, and large brackish seas and inland
Author(s): The Open University

A great many biological species and individuals occur in normal streams. These often differ markedly in their sensitivity to environmental factors, and likewise the tolerances of various species to different types of pollution vary considerably. The major groups of organisms that have been used as indicators of environmental pollution include bacteria, fungi, protozoa, algae, higher plants, macroinvertebrates and fish. The benthic 'bottom living' macroinvertebrates are particularly suitable a
Author(s): The Open University

Entry of precipitation through the soil surface and on downwards, by gravity, is known as infiltration. The rate at which this process can take place is governed by the permeability (a measure of the ease with which water can flow through the subsurface layer) and by the existing degree of saturation of the soil. Infiltration can be impeded by outcropping impermeable rocks or by paved areas, and also by the presence of finegrained soils with a low permeability (such as clay). At certain times
Author(s): The Open University

An additional possibility was considered. It was known that there was significant movement of the bridge during passage of traffic, because users had noticed it many times when crossing. The joints would thus have been subjected to rotary motion around the pin in order to accommodate such vibrations. Could these have caused fatigue crack growth at the bearing surfaces?

Contact between a circular and a flat plate creates so-called Hertzian stresses at the contact zone: compressive at the
Author(s): The Open University

It was important to establish the precise sequence of events leading up to and during the collapse. From which part had the collapse started? Why had so much of the structure been destroyed? Was there any prior warning of the failure? What part had the weather conditions at the time played?

Eyewitnesses were plentiful, and each had a different perspective of the bridge as it fell. There were some common parts to their statements. Most of the witnesses, especially survivors from vehicles
Author(s): The Open University

The Graeco-Roman city of Paestum
What can archaeological remains tell us about early cities and the people who lived in them? This album examines the important remains of one city, Poseidonia inÂ Italy, founded towards the end of the 7th century BCE by colonists from the Greek city of Sybaris. Although only twenty-five per centÂ of the site has been excavated to date, much of its history and culture can be traced throughÂ its buildings, inscriptions, and decoration. After it became a colony of Rome in 273 BCE, it became known a
Author(s): The OpenLearn team

An introduction to material culture
This free course, An introduction to material culture, introduces the study of material culture. It asks why we should study things and outlines some basic approaches to studying objects. Dr Rodney Harrison.
First published on Mon, 11 Jan 2016 as Author(s):
Dr Rodney Harrison

This free course provided an introduction to studying the arts and humanities. It took you through a series of exercises designed to develop your approach to study and learning at a distance and helped to improve your confidence as an independent learner.

Author(s): The Open University

Facilitating group discussions
Gain an insight into facilitating meetings and discussions in the workplace. In this free course, Facilitating group discussions, you will look at some of the behaviours effective facilitators exhibit. Informative and engaging videos will introduce you to examples of facilitation in practice. First published on Mon, 29 Feb 2016 as Author(s): Creator not set

The final meeting is a time for celebrating successful completion. It could have a similar format to the launch meeting, and involve many of the same people. It might include:

• reviewing the outputs or outcomes;

• confirming the arrangements for any follow-up work;

• thanking the team, the sponsor(s) and the stakeholders for their support;

• presenting the completion report for approval and sign-off.

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Author(s): The Open University

Critical social work practice
This series of tracks looks at social work practice around the world and compares attitudes and management techniques within the social work field. Material is taken from The Open University Course K315 Critical social work practice. The OpenLearn team.
First published on Tue, 13 Apr 2010 as Author(s):
The OpenLearn team

This free course provided an introduction to studying Computing and ICT. It took you through a series of exercises designed to develop your approach to study and learning at a distance and helped to improve your confidence as an independent learner.Â

Author(s): The Open University

What children and young people say
This free course, What children and young people say, looks at how practitioners and other adults talk to children and young people, and considers how this influences what they tell us. It identifies how children and young people would prefer to be engaged with, what would encourage their confidence in authority figures, and outlines the ways in which adults can improve on their listening techniques.Author(s): Creator not set

Issues in research with children and young people
This free course, Issues in research with children and young people, considers the aims and range of research with children and young people. Students consider how their own views and understandings about childhood and youth have arisen. Different definitions of research are explored through first-hand accounts by researchers across a range of disciplines and studies, from the small-scale to international studies studying children's lives across several countries. Attention is drawn to the role
Author(s): Creator not set

Learning to learn: Exploring learning
In this free course, Learning to learn: Exploring learning, we encourage you to consider two additional perspectives that can illuminate your learning. The first is the perspective that other people you know can provide; the second is the perspective that can be provided by academic theories about learning. We think that these two perspectives can help you prepare for personal change. PLEASE NOTE: this course is currently being reviewed. An updated and improved version of the course can be found
Author(s): Creator not set