IYPT 2012

 Programa Preliminar da IYPT 2012 ( fonte, IYPT Germany: https://iypt.wordpress.com/2011/08/02/25-iypt-2012-tasks/)

1. Gaussian cannon: A chain of identical steel balls and a strong magnet (somewhere
in the chain) are lying in a nonmagnetic channel. A further steel ball rolls slowly
towards the chain and collides. The last outgoing ball in the chain is shot away
faster, than you would imagine. Optimize the magnet’s position for the largest
effect.

2. Cutting through the air: When a piece of thread (e.g., nylon) with a light mass
attached at its end is whirled in the air, a distinct noise is emitted. Study the
origin of this noise and relevant parameters.

3. Chain of beads: A long chain of beads is released from a beaker
by pulling a sufficient long part of the chain over the edge of
the beaker. Due to gravity the speed of the chain increases. At a
certain moment the chain does not touch the edge of the beaker
any more (see picture). Investigate and explain the phenomenon.

4. Fluid bridge: If high voltage is applied to a fluid (e.g. water) in two beakers, which
are in contact, a fluid bridge can be formed. Investigate the phenomenon.

5. Bright waves: Illuminate a water tank. When there are waves on the water surface,
you can see bright-dark patterns on the bottom of the tank. Study the relation
between the waves and the pattern.

6. Woodpecker toy: A woodpecker toy (see picture) exhibits an oscillatory
motion. Investigate and explain the motion of the toy.

7. Drawing pins: A drawing pin floating on the surface of water near a similar floating
object is subject to an attractive force. Investigate and explain the phenomenon.
Is it possible to achieve a repulsive force as well?

8. Bubbles: Is it possible to float on water, when there are large amounts of bubbles?
Study how the floating of the body depends on the bubbles.

9. Magnet and coin: Put a coin vertically on a magnet. Incline the
coin and then release it. The coin may fall down onto the magnet
or reconvert to its vertical position. Study and explain the
coin’s motion.

10. Rocking bottle: Fill a water bottle with some liquid. Lay it down on a horizontal
plane and give it a kick. The bottle may move forward and then oscillate before
it comes to a full stop. Investigate the motion of the bottle.

11. Flat flow: Fill a thin gap between two large transparent horizontal parallel plates
with a liquid and make a little hole in the centre of one of the plates. Investigate
the flow in such a cell, if a different liquid is injected through the hole.

12. Lanterns: Paper lanterns float using a candle. Design and make a lantern using
a single tea-light to take the shortest possible time (from lighting the candle)
to float up a vertical height of 2.5m. Investigate the influence of the various
parameters.

13. Misty glass: Blow on a cold glass with your mouth so that water mist condenses
on the glass surface. Look at a white lamp through the misty glass, you can see
dim colourful rings appear outside the central fuzzy white spot. Explain the
phenomenon.

14. Granular jets: When a marble or ball bearing is dropped onto a bed of fine, loose
sand there will be a broad splash of sand at impact and, after the marble has
penetrated deeply into the bed, a tall jet of granular material that shoots up
vertically. How are these jets formed and what keeps them so collimated?

15. Frustrating golf ball: It often happens that a ball (e.g. a golf ball) escapes from a
cylindrical hole an instant after it has been putted in. Explain this phenomenon
and investigate the conditions under which it can be observed.

16. Rising bubble: A vertical tube is filled with a viscous fluid. On the bottom of the
tube, there is a large air bubble. Study the bubble rising from the bottom to the
surface.

17. Ball in foam: A small, light ball is placed inside soap foam. The size of the ball
should be comparable to the size of the foam bubbles. Investigate the ball’s motion
as a function of the relevant parameters.

^{Dica por Caroline}