Tag: physics

Just give me a second…

On the 30th June 2015 an extra second was added to clocks across the world. Seeing as you now have all of this extra time, here’s everything you need to know about the leap second…

  • The leap second arises because the atomic clocks that we use today are actually more accurate than the earth at time keeping – one million times more accurate to be exact.
  • Changes in the Earth’s orbit are influenced by a number of factors: from an occasional wobble to a gradual slowing of its rotation. This causes the Earth to speed up and slow down unpredictably and is the reason why we need to add leap seconds.
  • A total of 27 leap seconds have been added since 1972 when the idea was first introduced.
  • The last leap second was added at midnight on December 31st 2016, but due to the unpredictability of the Earth’s orbit I can’t actually tell you when the next one will be!
  • Don’t worry though, all electronic devices are updated automatically so long as they’re connected to the internet.

You can listen to the 2015 announcement with the Naked Scientists here.

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JFM China Symposia: Beijing

Video highlights from the third and final stop of the JFM China Symposia in Beijing. We were hosted by Tsinghua University with further speakers from Peking University, Xidian University, Beihang University and the Chinese Academy of Sciences.

Ke-Qing Xia describes how water in the ocean travels the entire globe over the course of 1000 years

 

Colm Caulfield explains how to the shape of a hanging chain is related to turbulence

 

Charles Meneveau discusses wind energy and its future as the current cheapest form of energy in the US

 

Photo: Christian Steiness

 

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JFM China Symposia: Hangzhou

I’m in China this week documenting the JFM Symposia ‘from fundamentals to applied fluid mechanics’ in the three cities of Shenzhen, Hangzhou and Beijing. Check out the CUP website for daily blog entries as well as some of my favourite video highlights from the scientific talks in Hangzhou below.

Detlef Lohse describes how a good scientist must be patient like a good bird-watcher as demonstrated by his experiments with exploding ice droplets

Hang Ding discusses falling droplets and shows a video of one hitting a mosquito

Quan Zhou presents some amazing visuals of Rayleigh-Taylor turbulence 

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Can you pee on the moon?

Question

If, in some miraculous way, one were able to pee standing on the surface of the Moon, what kind of arc would it create?

Answer

Dr Chris Messenger from the University of Glasgow was on hand to help me with Michael’s question…

  • The moon’s gravity is 16% of that on Earth, which means the pee will travel in a straighter arc and about 2.5 times further
  • In a uniform gravitational field objects travel in a parabolic arc – sort of a ‘u-shape’
  • On the moon, the atmosphere is so thin that the pee would follow a very accurate parabola, as can be seen with the dust thrown up by the lunar rover
  • The low atmospheric pressure on the moon would immediately boil the pee which would then fall to the surface as steam
  • Despite the low temperature of the moon (as low as -170 degrees Celsius), the pressure reduces the boiling point of water so dramatically that your pee would boil way below body temperature of 37 degrees Celsius, which is why it immediately turns to steam
  • The freezing temperature of water on the moon also occurs in the same range as the boiling point, which means that the steam molecules will then freeze into yellow ice crystals

You can listen to the full version of Question of the Week with the Naked Scientists here.

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The Next Large Hadron Collider

At the end of May 2017, scientists from all over the world met in Berlin to discuss the successor to the Large Hadron Collider, the particle accelerator at CERN. The new one is called the Future Circular Collider, or FCC, which will be up to three times larger and seven times more powerful than the current LHC aiming to simulate energy levels much closer to those seen during the ‘Big Bang’. I heard about the project from physicist Carsten Welsch at the University of Liverpool…

  • The new FCC aims to give us access to higher energy levels and ultimately take us closer to the conditions seen at the ‘Big Bang’ in order to discover further new particles such as the Higgs Boson.
  • Currently, the performance of the LHC is limited by the technology of magnets, which are needed to bend the particle beam around the 27 kilometre loop. The FCC will need stronger magnets or a larger tunnel.
  • Discoveries from particle physics have led to applications such as the internet, mobile communications and NMR diagnostics in hospitals.
  • The FCC project consists of an international community of academics who are looking into what will be required to build the new machine.
  • 20 years in the future the LHC will come to the end of its lifetime and so we need to act now to engage school kids today to think about a career in science.

 

You can listen to the full interview for the Naked Scientists here.

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Equations Stripped: Newton’s Law of Gravity

I strip back some of the most important equations in maths so that everyone can understand…

Newton’s Law of Gravity not only explained why apples fall to the ground, it also laid the foundations for modern-day physics by using equations to describe the world around us.

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Shocking Science of Electric Eels

Following on from my discussion on BBC Radio Cambridgeshire about the scientist electrocuting himself with electric eels I got to interview the man himself for the Naked Scientists…

In the 1800s, whilst exploring the Amazon, naturalist Alexander von Humboldt documented an attack on a horse by an electric eel, which allegedly leapt out of the water to stun the animal… Yet despite being studied for over 200 years since, this – and the video on YouTube below – were the only documented claims of this behaviour, until, that is, Vanderbilt University’s Ken Catania got his hands on an electric eel. Literally…

  • Electric eels use their shock to freeze-up animals for predation
  • Ken discovered the leaping behaviour when an eel jumped out of the water to attack the net that he was holding
  • He wanted to measure all of the variables in the electric circuit formed by the eel and its prey
  • To do this he used himself as bait and allowed the eel to shock his arm so that he could measure the current and resistance
  • The small eel he was working with gave off 200 volts but larger ones could reach up to 500 – the equivalent of 20 tasers
  • The current of 40-50 milliamps flowing through his arm was sufficiently painful to cause an involuntary reflex action to remove his arm

You can listen to the full interview here.

 

 

 

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