Physics is in the Air

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NEWSLETTER – July 22th 2012 Issue nO.8

Photo: Henry Teigar

What will be the final score?

How do they see Estonia?

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he examinations are over and before the final scores are announced the students can have fun and explore the country without any pressure. Yesterday all the delegations said goodbye to Tartu and headed to Tallinn. The IPhO media team talked to participants from 6 from different geographic regions and asked them what they thought about their stay and what were their plans for the rest of it. Team Australia thought that so far Estonia had been awesome! “You have really good WiFi and it’s free! The Nature is pretty and everybody speaks such good English,“ they said. When asked what they missed from home, the answer was “nothing“. But Siobhan, the only girl in the team said: “I only miss my horses.“ Before leaving they planned to have a sauna party. “We are very excited about that. I’ve never been to a sauna,“ said Nick. Like the Aussies, the Romanian students were also impressed by the range of WiFi.

“You even have it in the buses. Do you have it everywhere?“ they were pleasantly surprised. The Romanians planned to go to a cinema in Tallinn. “We found a really cool cinema on the roof of a shopping centre where they show only classic films. Tonight there´s an Italian movie.“ Among the Estonians words they had learned was the greeting “Tere!“ Jeffrey C. from USA knew how to count from 1 to 10 in Estonian. Students from the USA said that they will miss the other IPhO contestants and their accents. “It’s so cool, how everybody has an unique accent,“ said Jeffrey Y. He thought the coolest was Australian. Some of the memorable happenings for the students were ice cream eating in the middle of night or singing along „We will rock you“ with the mayor of Tartu. After check in at the hotel Viru, competitors from the Syrian team went off to do a little shopping in Tallinn’s biggest shopping centres, Viru and Solaris. However, although they had just arrived in Tallinn, they were already certain they liked Tartu more. “It´s

Happy contestants from Australia.

more quiet and not so crowded in Tartu. And there are more green places. We loved it. Tartu is just like a big village,“ they asserted. The first thing the Colombian students did after check in was to hit the shops to buy gifts and souvenirs for their families. “In Estonia there are so many good shopping places, even outside of the centres!“ said an impressed Andres. The students were also surprised about the local traffic. “It is surprising that when you want to cross the road, the cars stop and let you pass.“ The South-Africa delegation planned to prepare for today’s football match. “We will win the tournament!“ Xolela was sure. Members of the South-Africa team also wished that they could have some cheerleaders. In some ways Estonia was more different than they thought. “A friend of ours said that it is not a modern country,“ said the student, who was surprised at the level of local development. Text: Saile Mägi, Anete Sammler, Liisi Sünd


Agreeing the final scores

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Photo: Merily Salura

he moderator and leaders of each team had to reach an agreement about the fairness of the marking. This was done by private discussion with the leaders individually. All of them had analysed the marked papers before, so they just needed to agree the final scores during the 20 minutes allowed. If the leaders had already reached the same conclusion about the results before the discussion with the moderator, then moderation would not go ahead. To read about the emotions after moderation, check out the interviews online www.ipho2012.ee/newsletter Text: Brenda Rauniste

Football match Read more what people from different continents think about Estonia and what they have been doing here. Also we are sharing the experience of the visit to the Saku brewery, detailes and interviews about moderating! Check it out from: www.ipho2012.ee/newsletter

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fter constant accumulation of tension and suspense during the examination week, Sunday July 22 offers all participants an option to unwind over a few friendly games of football. Currently 64 teams comprising five players have registered for this mini-tournament organized on the penultimate day of IPhO 2012. Due to significant interest and the large number of participants, no winners or final positions will be recorded. Each team is scheduled three games of 15 minutes against a predetermined opposition. The first games

start at 9.30 at the sports ground of Pirita Gymnasium of Economics where plenty of supporters are expected to cheer the teams on. Text: J체ri L천ssenko Organizer of the football tournament

Kevin Zhou

Wai Hei Hoi

Photo: Siim Pille

Happy Birthday!

Friendly practice between Turkmenistan and South Africa.


Photo: Merily Salura

Syrian Arab Republic team enjoying majestic view of the Old Town.

Getting information from USA contestants.

Photo: Andres Mihkelson

In good company. Colombian delegation.

Photo: Henry Teigar

Romenian team chilling in the fresh air.

Photo: Andres Mihkelson

Contestants enjoying greenery of Tallinn.

Photo: Andres Mihkeslon

Photo: Henry Teigar

Picture gallery

Passing time at the lobby of Sokos Hotel Viru.


Delegates

Feynman’s Corner A smart cut (solution)

brainden.com/geometry-puzzles.htm

Sausage grilling (solution)

Coffee foam

The stress in the skin will be anisotropic, and the crack direction corresponds to the direction of stronger stress. Suppose that there is an excess pressure p inside the sausage. Let the sausage length l be much larger than its radius – r. Consider an axial cut of the sausage: the two halves of the sausage are pushed due to the excess pressure with a force equal to 2rlp (where rl is the cross-sectional area), and pulled due to the stress σ1 in the skin with a force equal to 2l σ1 (where 2l is the perimeter of the cross-section). Since these two forces balance each other, σ1 = rp. Now, let us consider a cross-section perpendicular to the sausage: proceeding in the same way as above we obtain πr2p = 2πr σ2, hence σ2 = rp / 2. The first stress is twice as large as the second one, so, of course, the crack will form along the sausage.

Coffee is black, but its foam is white (or creamy). Why? A smart hit How should a player located at S inside the corner ÐAOC hit the ball to get it back after two bounces from the walls OA and OB?


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