![]() ![]() In fact, most substances become more dense when they freeze. Most solids, such as rocks, are more dense than liquids, so they sink. The reason ice floats is due to a strange quirk of water. ![]() This is why hot air rises, because it has become less dense than ambient air and so ‘floats’ to the top. Heat energy causes molecules in air to vibrate, and so the average distance between molecules increases, decreasing the density. Intuitively, water will be heavier than air.įrom a physics perspective, we actually say that “hot air” rises, rather than heat. Water is lot more dense than air, because the molecules are closer together. "Whether something rises or sinks is to do with the relative density of matter. It’s weird that heat rises, but ice floats. This lowers the temperature of the fire and without heat, a fire cannot continue to burn." The reason that water puts out fire is fairly simple - water absorbs a lot of heat energy. Therefore, the oxygen in water has already ‘oxidised’ and isn’t free to contribute to further combustion, or burning. The creation of water is actually due to the combustion of hydrogen, which produces energy. When hydrogen and oxygen combine to create water, an entirely different molecule is created. In reality, oxygen does not burn - in fact, oxygen acts as a ‘oxidiser’ and lowers the ignition temperature of other compounds, rather than burning itself. However, it is a common misconception that oxygen is also flammable. ![]() "Flammability is defined as the ability of a material to sustain enough heat energy to keep a fire going, given enough oxygen. Lily Clarke, Physics consultant for Innovia Technology Put 'em together and you can put out fires. The online whirlpool that creates is hugely distracting, and not very useful when it comes to inspiring trust in the media, which is such an important tool in holding power to account." People see a headline, make an assumption, and share, often before even reading a piece. The saying ‘a lie travels around the globe while the truth is putting on its shoes’ has never been more resonant when people are so quick to leap on and share any hint of bias confirmation on social media. The shortening of the news cycle has also amped up the stakes hugely. So while fake news is a very real problem in and of itself, its use as a political football can be even more dangerous and confusing - especially when coverage of accusations of fake news gets a bigger reaction than ‘real’ news coverage. I find it almost impossible to remember a time before fake news, as it’s so ubiquitous now! I think it’s very telling that the people making the loudest accusations of fake news are also often the worst culprits of it. Holly Thomas, Freelance journalist for CNN It isn't though true to say the edges of the Moon significantly focus sunlight on to the Earth. At all other times the bright light of the Sun can permanently damage your eyes, and you should also *never* look at it through binoculars or a telescope without properly certified filters. Looking directly at the Sun is a *really bad idea*, except during the total phase of a total solar eclipse, when its brightest surface is completely blocked by the Moon. Sadly we're now influencing our own climate through CO2 emissions, and that's happening on a much shorter timescale. Fortunately the output of the Sun has only varied by a small amount over the whole of human history and prehistory, though in hundreds of millions of years it will be significantly brighter. Without the electromagnetic radiation it emits (reaching us in the form of radio waves, light, ultraviolet light and infrared light) we would live on a cold, dark world. "The Sun is certainly vital for advanced life on Earth. Today its power will be enough to blind you just by looking at the outer edges of it concentrated by the moon.ĭr Robert Massey, Deputy Executive Director, Royal Astronomical Society. A ball of fire millions of miles away that can vastly affect climate on the surface of the earth by traveling just thousands of miles. The power of the sun will never cease to amaze me. ![]()
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