Problems of the 11th IYPT
(official version 97/10/15)
1. Invent yourself
Construct an aeroplane from a sheet of paper (A4, 80 g/m²). Make
it fly as far and/or as long as possible. Explain why it was
impossible to reach a greater distance or a longer time.
2. Popping body
A body is submerged in water. After release it will pop out of the
water. How does the height of the pop above the water surface depend on the initial conditions (depth and other parameters)?
3. Spinning disc
Investigate and explain the phenomenon of a spinning annular disc as
they progress down a straight, cylindrical rod. If the rod is moved
upwards at a defined velocity, the disc spins at constant
height. Investigate the mechanism.
4. Water streams
A can with three holes in the side-wall at the same height slightly
above the bottom is filled with water. The water will escape in three
separate streams. By gently touching the streams with a finger they
may unite. Investigate the conditions for this to happen.
5. Water jet
If a vertical water jet falls down onto a horizontal plate,
standing waves will develop on the surface of the jet. Investigate the
dependence of this phenomenon on different parameters.
6. Mount Everest
Can you see Mount Everest from Darjeeling?
7. Air bubble
An air bubble rises in a water-filled, vertical tube with
inner diameter 3 to 5 mm. How does the velocity of the rising bubble
depend on its shape and size?
It is known that a glass filled with water and covered with a sheet of
paper may be turned upside down without any loss of water. Find the
minimum amount of water to perform the trick successfully.
9. Woven textiles
Look at a point-like light source through different woven
textiles. Describe what you see. What is the explanation of the phenomenon?
10. Repeated freezing
While a vessel filled with an aqueous solution of a volatile
fluid, e.g., ammonia, ethanol or acetone, is being cooled, repeated
freezing and melting may be observed near the surface. Describe and
explain the phenomenon.
11. Current system
In a Petri dish (shallow bowl), small metal balls, e.g., 2 mm in
diameter, are immersed in a layer of castor oil. The inner rim of the
dish contains an earthed metal ring. Above the centre of the dish
there is a metal needle which does not touch the oil
surface. Investigate what happens when the voltage between needle and
earth is about 20 kV.
Warning: The high voltage should be obtained by means of a safe generator,
e.g., an electrostatic generator!
12. Powder conductivity
Measure and explain the conductivity of a mixture of metallic and
dielectric powders with various proportions of the two components.
How is it possible that a very long and strong rope can be produced
from short fibers? Prepare a rope from fibers and investigate its
14. Water rise
Immerse the end of a textile strip in water. How fast does the water
rise in the strip and what height does it reach? In which way do these
results depend on the properties of the textile?
15. Luminescent sugar
Investigate and explain the light produced when sugar crystals are
pulverized. Are there other substances with the same property?
16. Strange motion
Make a mixture of ammonium nitrate and water, proportion 5 to
1. When the mixture is heated to about 100 °C it melts. When it cools,it
crystallizes and you may observe a strange motion below the
surface. Investigate and explain the phenomenon.
Safety rules: Do not heat the ammonium nitrate without water,
preferably use a water bath!
Use protection glasses during the experiment!
Investigate and explain the formation of icicles.