4.1 The experimental result

One way to establish the speed of sound is to measure it experimentally. That is, one measures how long the sound takes to travel a known distance, and from this works out the speed. The answer turns out to depend somewhat on the prevailing temperature and humidity. At an air temperature of 14 °C the speed is 340 metres per second and at about 22.5 °C it is 345 metres per second. That is a change of speed of less than 1.5 per cent for an appreciable change of temperature. To a reasonable ap
Author(s): The Open University

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Special Relationship: Don't Believe the Liberal Media?
The media is under siege in this election — and the phenomenon isn't limited to the campaign for U.S. president. In this episode, Celeste and John talk with two powerful news editors in the United States and Europe about covering politics in an era when people think they're entitled not just to their own opinions, but their own facts. Marty Baron, the Pulitzer Prize-winning executive editor of The Washington Post, speaks about the moral obligation — and occasional frustrations — of truth
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Ocean Acidification Symposium - Ocean Acidification- the other CO2 problem
The Ocean Acidification Symposium was presented by the Centre for Chemical and Physical Oceanography, in November of 2012. The day-long symposium featured brief presentations from a wide range of researchers, of which this is one: Katie Baer Jones talks about the impact of Ocean Acidification on coralline algae and iconic shellfish such as Paua and oysters. Increases in the total dissolved inorganic carbon in the ocean lower the pH in the ocean, reducing the availability of carbonate ions for th
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1 Maxwell's greatest triumph

This course presents Maxwell's greatest triumph – the prediction that electromagnetic waves can propagate vast distances through empty space and the realisation that light is itself an electromagnetic wave. Visible light has a very narrow range of wavelengths, but this tells us more about the sensitivity of our eyes than about the nature of electromagnetic radiation. A few years after Maxwell's death other types of electromagnetic radiation, including radio waves, X-rays and gamma rays, wer
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#248: Prey to temptation: Our struggle with irrational health choices

Social epidemiologist Prof Ichiro Kawachi describes how mental short-cuts affect our health choices, often for the worse, and what can be done to help us make better choices. Presented by Dr Dyani Lewis.