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wave mechanics

4. Series 21. Year - 3. roaring volcano

Recently there was a TV document about the eruption of Krakatoa volcano in August 1883. Remarkably the noise of eruption deafened for while people in distance 50 km from volcano. The sound of eruption was heard as distant thunder in town Alice Springs in Central Australia (approx 5 000 km from the volcano).

What was the value of acoustic pressure in dB at the place of eruption?Can we assume, that the decrease of intensity follows inverse square law? Or should we define a different rule in this case?

Úlohu vymyslel pan Janata inspirován zmíněným dokumentem.

6. Series 20. Year - P. how the UFO-man is looking?

In this problem question think about and animal, which communicate at radio frequency (10 Hz –100 MHz). Suggest an biological equivalent of necessary radio-electronic components.

Zadal Michael Komm doufaje, že přijdete na něco zajímavého.

5. Series 20. Year - 1. dead pianist

The pianist falls from the skyscraper. During the fall he is playing tone A on piano. Exactly $k$ floor lower is window cleaning man. What is value $k$, if the last thing the window cleaning man heard is tone Ais (half-tone higher then A)? Speed of sound is 347 m\cdot s^{ − 1}, height of one floor is 3,1 m.

Morbidní úlohu navrhl Petr Sýkora.

2. Series 19. Year - P. wind instruments

Explain, why is it possible to 'over-blow' (play one octave higher than normally) a flute, and it is not possible with clarinet.

Staré návrhy.

6. Series 18. Year - E. catch a photon

Measure the speed of light in vacuum. Use any method, for example use microwave oven.

Co jiného dát jak exp do roku fyziky.

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