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IYPT 역대 문제

제25회(2012년)

The Regulations of the IYPT (2009년 개정)
I. International Young Physicists’ Tournament

The International Young Physicists’ Tournament (IYPT) is a competition among teams of secondary school students in their ability to solve complicated scientific problems, to present solutions to these problems in a convincing form and to defend them in scientific discussions, called Physics Fights (PF).

II. The problems of the IYPT

The 17 problems are formulated by the International Organizing Committee (IOC) and sent to the participating countries not later than in October. These problems may be used in any competition that could lead to selection of a national team. They may be used in International tournaments that involve foreign teams not taking part in IYPT.

III. The participants of the IYPT
  • 1. The national teams

    Any invited country, as well as the host country, is represented by one team. A country can only take part in the IYPT that has already taken part in the past or sent an observer in one of the last three years.

  • 2. The membership of the teams

    The IYPT team is composed of five secondary school students. The secondary school graduates could participate in the IYPT in the year of their graduation. The participation of university students is not allowed. The LOC may allow participation of teams of four or three students. The composition of the team cannot be changed during the Tournament. The team is headed by a captain who is the official representative of the team during the PF.

  • 3. The team is accompanied by two team leaders.
IV. The Jury

The Jury is nominated and organized by the LOC in cooperation with EC. The Jury consists of at least five members, if possible from different countries. Team leaders, at least one from each team, are included in the Jury. The team leaders cannot be members of the Jury in the PF where their teams participate and should not, if possible, grade the same team more than twice.

V. The agenda of the IYPT

The IYPT is carried out in a period determined by the LOC (from May to July). All teams participate in five Selective PFs. Selective PFs are carried out according to a fixed schedule as detailed in the attachment to these Regulations. Numbers are ascribed to teams by lot. The best teams participate in the Final PF. The host country provides a cultural program for the participants.

VI. The Physics Fight regulations

Three or four teams participate in a PF, depending on the total number of teams. In the course of a PF the members of a team communicate only with each other. Before the beginning of a PF, the Jury and the teams are introduced. The PF is carried out in three (or four) Stages. In each Stage, a team plays one of the three (four) roles: Reporter, Opponent, Reviewer (Observer). In the subsequent Stages of the PF, the teams change their roles according to the schemes:

  • Three teams PF
    Three teams PF
    Stage/Team 1 2 3
    A Rep Rev Opp
    B Opp Rep Rev
    C Rev Opp Rep
  • Four teams PF
    Four teams PF
    Stage/Team 1 2 3 4
    A Rep Obs Rev Opp
    B Opp Rep Obs Rev
    C Rev Opp Rep Obs
    D Obs Rev Opp Rep
VII. The Stage regulations
2. PF에서의 제한 시간
The performance order in the Stage of a PF Reserved time(min)
The Opponent challenges the Reporter for the problem 1분
The Reporter accepts or rejects the challenge 1분
Preparation of the Reporter 5분
Presentation of the report 12분
Questions of the Opponent to the Reporter and answers of the Reporter 2분
Preparation of the Opponent 3분
The Opponent takes the floor, maximum 5 min. and discussion between the Reporter and
the Opponent
15분
Questions of the Reviewer to the Reporter and the Opponent and answers to the questions 3분
Preparation of the Reviewer 2분
The Reviewer takes the floor 4분
Concluding remarks of the Reporter 2분
Questions of the Jury 5분
  • In the Final PF the procedure of challenge is omitted.
  • The official language of the IYPT is English.
VIII. The team performance in the Stages

The Reporter presents the essence of the solution to the problem, attracting the attention of the audience to the main physical ideas and conclusions.

The Opponent puts questions to the Reporter and criticizes the report, pointing to possible inaccuracy and errors in the understanding of the problem and in the solution. The Opponent analyses the advantages and drawbacks of both the solution both thpresentation of the Reporter. The discussion of the Opponent shoulotnot become a presentation of his/her own solution. In the discussion, the solution presented by the Reporter is discussed.

The Reviewerpresents a short estimation of the presentations of Reporter and Opponent.

The Observerdoes not participate actively in the PF.
During one PF only one member of a team takes the floor as Reporter, Opponent or Reviewer; other members of the team are allowed to make brief remarks or to help with the presentation technically. No member of a team may take the floor more than twice during one Selective PF or, as Reporter, more than three times in total during all Selective PFs. During the Final PF any team member can take the floor only once.
The LOC must inform about the devices available for presentations not later than two months before the IYPT.

IX. The rules of problem-challenge and rejection
  • 1. All problems presented in the same PF must be different.
  • 2. Selective PF
    The Opponent may challenge the Reporter on any problem with the exception for a problem that:
    • a) was rejected by the Reporter earlier;
    • b) was presented by the Reporter earlier;
    • c) was opposed by the Opponent earlier;
    • d) was presented by the Opponent earlier.
  • If there are less than five problems left to challenge, the bans d), c), b), a) are successively removed, in that order. During the Selective PFs the Reporter may reject the challenge of three different problems in total without penalty. For every subsequent rejection the coefficient of the Reporter (see section X) is decreased by 0.2. This reduction continues to apply during the following selective PFs.
  • 3. Final PF
    Within four hours after the announcement of the results of the Selective PFs the teams participating in the Final choose their problems. In case teams choose the same problem, priority is given according to the order of presentation in the Final (see section XII). The choice should be made public immediately.
X. The grading

After each stage the Jury grades the teams, taking into account all presentations of the members of the team, questions and answers to the questions, and participation in the discussion. Each Jury member shows integer marks from 1 to 10. The mean of the highest and the lowest marks is counted as one mark which is then added to the remaining marks. This sum is used to calculate the mean mark for the team. The mean marks are multiplied by various coefficients: 3.0 or less (see section IX) for the Reporter, 2.0 for the Opponent, 1.0 for the Reviewer and then transformed into points.

XI. The resulting parameters
  • 1. For a team in the PF

    The sum of points (SP) is the sum of mean marks, multiplied by the corresponding coefficients and rounded to one decimal.

  • 2. For a team in the Tournament

    The total sum of points (TSP) equals the sum of SP of the team in all Selective PFs. The number of fights won (FW) is the number of Selective PFs, in which a team received the highest SP from all three or four teams participating in the same PFs.

XII. The Final

The three teams having the highest TSP in the Selective PFs participate in the Final. In case teams have equal TSP, their participation in the Final is decided by FW. If team(s) winning all their Selective PFs (FW=5) did not reach the Final by TSP, the best of them (determined by TSP) takes part in the final as fourth team. The order of presentation in the Final is determined by position by entering the final: the higher the position, the lower the number in the scheme of section VI.

XIII. The final team ranking of the IYPT

Students in the top half (rounded up) of participating teams receive medals. The students of the team winning the Final are awarded the winners’ cup. If two or three teams have the same SP result in the Final, the winner is nominated according to the highest TSP, in case of equality by FW. All teams participating in the final are awarded 1st place certificates and gold medals. The five best teams not participating in the final are awarded 2nd place certificates and silver medals. 3rd place certificates and bronze medals are awarded to students in all other teams finishing in the top half. All other students receive certificates of participation. Team leaders obtain certificates indicating the ranking of their team.

XIV. The status of the regulations of the IYPT

The regulations are established by the IOC and may be changed only by the IOC.

제24회(2011년)

Problems for the 24th IYPT, July 2011 Iran, Tehran
1. Adhesive tape

Determine the force necessary to remove a piece of adhesive tape from a horizontal surface. Investigate the influence of relevant parameters.

2. Air drying

Table utensils (dishes, cutlery, etc.), after being washed, dry differently. Investigate how the time of drying depends on relevant parameters.

3. Bouncing flame

Place a flame (e.g. from a Bunsen burner) between two charged parallel metal plates. Investigate the motion of the flame.

4. Breaking spaghetti

Find the conditions under which dry spaghetti falling on a hard floor does not break.

5. Car

Build a model car powered by an engine using an elastic air-filled toy-balloon as the energy source. Determine how the distance travelled by the car depends on relevant parameters and maximize the efficiency of the car.

6. Convection

In a container filled with a liquid, heat transport will occur when the bottom of the container is heated and the top surface is cooled. How does the phenomenon change when the container rotates about its vertical axis?

7. Cup drum

A plastic cup is held upside-down and tapped on its base. Investigate the sound produced when the open end of the cup is above, on or below a water surface.

8. Domino amplifier

A row of dominoes falling in sequence after the first is displaced is a well known phenomenon. If a row of "dominoes" gradually increases in height, investigate how the energy transfer takes place and determine any limitations to the size of the dominoes.

9. Escaping powder

When a hot wire is plunged into a beaker of water with powder (e.g. lycopodium) floating on the surface, the powder moves rapidly. Investigate the parameters that alter the speed of movement of the powder.

10. Faraday heaping

When a container filled with small spheres (e.g. mustard seeds) is vibrated vertically with a frequency between 1 – 10 Hz, so called Faraday heaping occurs. Explore this phenomenon.

11. Fingerprints

Fill a glass with a liquid and hold it in your hands. If you look from above at the inner walls of the glass, you will notice that the only thing visible through the walls is a very bright and clear image of patterns on your fingertips. Study and explain this phenomenon.

12. Levitating spinner

A toy consists of a magnetic spinning top and a plate containing magnets (e.g. "Levitron"). The top may levitate above the magnetic plate. Under what conditions can one observe the phenomenon?

13. Light bulb

What is the ratio between the thermal energy and light energy emitted from a small electric bulb depending on the voltage applied to a bulb?

14. Moving cylinder

Place a sheet of paper on a horizontal table and put a cylindrical object (e.g. a pencil) on the paper. Pull the paper out. Observe and investigate the motion of the cylinder until it comes to rest.

15. Slow descent

Design and make a device, using one sheet of A4 80 gram per m2 paper that will take the longest possible time to fall to the ground through a vertical distance of 2.5m. A small amount of glue may be used. Investigate the influence of the relevant parameters.

16. Smoke stream

A glass jar is covered with cellophane. A tightly folded paper tube of length 4-5 cm is inserted hermetically into the jar through the cellophane cover. The tube is oriented horizontally. If one burns the outside end of the tube the dense smoke flows into the jar. Explore this phenomenon.

17. Vikings

According to a legend, Vikings were able to navigate in an ocean even during overcast (dull) weather using tourmaline crystals. Study how it is possible to navigate using a polarizing material. What is the accuracy of the method?

제23회(2010년)

Problems for the 23rd IYPT, July 2010 Vienna, Austria
1. Electromagnetic cannon

A solenoid can be used to fire a small ball. A capacitor is used to energize the solenoid coil. Build a device with a capacitor charged to a maximum 50V. Investigate the relevant parameters and maximize the speed of the ball.

2. Brilliant pattern

Suspend a water drop at the lower end of a vertical pipe. Illuminate the drop using a laser pointer and observe the pattern created on a screen. Study and explain the structure of the pattern.

3. Steel balls

Colliding two large steel balls with a thin sheet of material (e.g. paper) in between may “burn” a hole in the sheet. Investigate this effect for various materials.

4. Soap film

Create a soap film in a circular wire loop. The soap film deforms when a charged body is placed next to it. Investigate how the shape of the soap film depends on the position and nature of the charge.

5. Grid

A plastic grid covers the open end of a cylindrical vessel containing water. The grid is covered and the vessel is turned upside down. What is the maximal size of holes in the grid so that water does not flow out when the cover is removed?

6. Ice

A wire with weights attached to each end is placed across a block of ice. The wire may pass through the ice without cutting it. Investigate the phenomenon.

7. Two flasks

Two similar flasks (one is empty, one contains water) are each connected by flexible pipes to a lower water reservoir. The flasks are heated to 100°C and this temperature is held for some time. Heating is stopped and as the flasks cool down water is drawn up the tubes. Investigate and describe in which tube the water goes up faster and in which the final height is greater. How does this effect depend on the time of heating?

8. Liquid light guide

A transparent vessel is filled with a liquid (e.g. water). A jet flows out of the vessel. A light source is placed so that a horizontal beam enters the liquid jet (see picture). Under what conditions does the jet operate like a light guide?

Liquid light guide

9. Sticky water

When a horizontal cylinder is placed in a vertical stream of water, the stream can follow the cylinder’s circumference along the bottom and continue up the other side before it detaches. Explain this phenomenon and investigate the relevant parameters.

10. Calm surface

When wind blows across a water surface, waves can be observed. If the water is covered by an oil layer, the waves on the water surface will diminish. Investigate the phenomenon.

11. Sand

Dry sand is rather 'soft' to walk on when compared to damp sand. However sand containing a significant amount of water becomes soft again. Investigate the parameters that affect the softness of sand.

12. Wet towels

When a wet towel is flicked, it may create a cracking sound like a whip. Investigate the effect. Why does a wet towel crack louder than a dry one?

13. Shrieking rod

A metal rod is held between two fingers and hit. Investigate how the sound produced depends on the position of holding and hitting the rod?

14. Magnetic spring

Two magnets are arranged on top of each other such that one of them is fixed and the other one can move vertically. Investigate oscillations of the magnet.

15. Paper anemometer

When thin strips of paper are placed in an air flow, a noise may be heard. Investigate how the velocity of the air flow can be deduced from this noise?

16. Rotating spring

A helical spring is rotated about one of its ends around a vertical axis. Investigate the expansion of the spring with and without an additional mass attached to its free end.

17. Kelvin’s dropper

Construct Kelvin’s dropper. Measure the highest voltage it can produce. Investigate its dependence on relevant parameters.

제22회(2009년)

Problems for the 22ndIYPT, 21-28 July 2009 Nankai University, Tianjin, China
1. Stearin engine

A candle is balanced on a horizontal needle placed through it near its centre of mass. When the candle is lit at both ends, it may start to oscillate. Investigate the phenomenon. Maximize the output mechanical power of the system.

2. Coupled compasses

Place a compass on a table. Place a similar compass next to the first one and shake it gently to make the needle start oscillating. The original compass' needle will start oscillating. Observe and explain the behaviour of these coupled oscillators.

3. Resonating modes

Place a mobile phone inside a metallic container with a hole in it. Investigate under what conditions the mobile phone starts to ring after calling it.

4. Ghostly images

Ghostly images

When a photo is taken with a flash, bright "disks" may appear as shown in the picture. Investigate and explain the phenomenon.

 

5. Stop a drip

To prevent dripping from a bottle after pouring, it can be turned slightly. Investigate the motion of the bottle for no drop to fall.

6. Roundabout

Put a plastic cup on a thin layer of liquid on a flat solid surface. Make the cup rotate. On what parameters does the rotational deceleration of the cup depend?

7. Skateboarder

A skateboarder on a horizontal surface can accelerate from rest just by moving the body, without touching external support. Investigate the parameters that affect the motion of a skateboard propelled by this method.

8. Air pocket

A vertical air jet from a straw produces a cavity on a water surface. What parameters determine the volume and depth of the cavity?

9. Drying

Investigate the drying process of a vertical wet paper sheet. How does the boundary of drying move?

10. Optical tube

Look down a cylindrical metal tube which is shiny on the inside. You will notice dark and light bands. Investigate the phenomenon.

11. Transformers

The "simple transformer law" relates output voltage to input voltage and turns ratio. Investigate the importance of frequency and other parameters in determining the non-ideal behaviour of transformers.

12. Hot ball

Put a hot metal ball on parallel horizontal rails. The ball starts to move. Investigate the phenomenon.

13. Sand ripples

Investigate how the formation of sand ripples under shallow water depends on various parameters.

14. Bouncing drop

Investigate the motion of water droplets falling on a hydrophobic surface (e.g. coated with soot or teflon).

15. Electro-oscillator

A mass is hung from the middle of a horizontal wire. When a current is passed through the wire, the mass may start to oscillate. Describe and explain this phenomenon.

16. Electromagnetic motor

Attach a strong light magnet to the head of a steel screw. The screw can now hang from the terminal of a battery. Completing the circuit by a sliding contact on the magnet causes the screw to rotate. Investigate the parameters that determine the angular velocity of the screw.

17. Corrugation

Corrugation

After traffic has used an unpaved road for some time the surface of the road gets a "wave" structure with a well defined wavelength. Investigate and explain this phenomenon.

 

제21회(2008년)

21st IYPT, 21-28 May, 2008, Trogir, Croatia
1. Tipcat

Place a small wooden stick over the edge of a desk. Hit the end of the stick overhanging the table so that it flies away. How is the flight distance related to the relevant parameters? What is the condition for a maximum horizontal distance?

2. Winged seed

Investigate the motion of falling winged seeds such as those of the maple tree.

3. Pin-hole Camera

Study the characteristics of a pin-hole camera and find the conditions for the camera to achieve optimum image quality.

4. Cymbal

Discharging an electronic flash unit near a cymbal will produce a sound from the cymbal. Explain the phenomenon and investigate the relevant parameters.

5. Voltaic cell

Make a voltaic cell using paper tissues as a salt bridge. Study and explain how the electromotive force of this battery depends on time.

6. Liquid stain

When a drop of liquid such as coffee dries on a smooth surface, the stain usually remains at the edge of the drop. Investigate why the stain forms at the edge and what parameters affect the characteristics of the stain.

7. Making a Splash

A solid object is dropped into water from a height of 50 cm. Investigate the factors that would minimize the splash.

8. Astroblaster

When a large ball is dropped, with a smaller one stacked on top of it, onto a hard surface, the smaller ball will often rise much higher than it would if dropped onto the same surface by itself while the larger ball hardly bounces at all. Investigate this phenomenon and design a multiple-ball system, using up to 4 balls, that will reach the greatest elevation of the top ball.

9. Flute

Drill a hole into the side of a tube that is open at one end and produce a sound by blowing the open end. Investigate the pitch and timbre of the sound of your flute and how they depend on the position and the diameter of the hole.

10. Kaye Effect

When a thin stream of shampoo is poured onto a surface, a small stream of liquid occasionally leaps out. This effect lasts less than a second but occurs repeatedly. Investigate this phenomenon and give an explanation.

11. Gutter

When a thin layer of water flows along an inclined gutter different wave patterns are sometimes observed. Study this phenomenon.

12. Geyser

Support a long, vertical tube containing water. Heat the tube directly from the bottom and you will observe that the water erupts. Arrange for the water to drain back into the tube to allow repeated eruptions. Investigate the parameters that affect the time dependence of the process.

13. Spinning ice

Pour very hot water into a cup and stir it so the water rotates slowly. Place a small ice cube at the centre of the rotating water. The ice cube will spin faster than the water around it. Investigate the parameters that influence the ice rotation.

14. Faraday Generator

Construct a homopolar electric generator. Investigate the electrical properties of the device and find its efficiency.

15. Gelation

Hot gelatine solution becomes a gel upon cooling. Investigate the electric conductivity as a function of temperature as it gels. Explain the results obtained.

16. Black spoon

Blacken a spoon using a candle flame. If you immerse the spoon in water it appears glossy. Investigate the phenomenon and determine the optical properties of such a "mirror."

17. Heat engine

Build a heat engine powered only by the difference between the day and night air temperatures without using direct sunlight. Determine its efficiency

제20회(2007년)

PROBLEMS FOR IYPT 2007: 5th to 11th June 2007 Sungnam, Korea
1. Filament

There is a significant current surge when a filament lamp is first switched on. Propose a theoretical model and investigate it experimentally.

2. Slinky

Suspend a Slinky vertically and let it fall freely. Investigate the characteristics of the Slinky's free-fall motion.

3. Water jets

What can be observed when two water jets collide at different angles?

4. Spring thread

Pull a thread through the button holes as shown in the picture. The button can be put into rotating motion by pulling the thread. One can feel some hoasticthe of the thread. ing motion bhoastic properties of such a system.

Spring thread

5. Razor Blade

A razor blade is placed gently on a water surface. A charged body brought near the razor makes it move away. Describe the motion of the razor if an external electric field is applied.

6. Rheology

It has been said that if you are sinking in soft mud, you should not move vigourously to try to get out. Make a model of the phenomenon and study its properties.

7. Crickets

Some insects, such as crickets, produce a rather impressive sound by rubbing together two parts of their body. Investigate this phenomenon. Build a device producing a sound in a similar way.

8. Condensation

Water droplets form on a glass filled with cold water. Explain the phenomenon and investigate the parameters that determine the size and number of droplets on the glass.

9. Ink Droplet

Place a droplet of ball pen ink on a water surface. The droplet begins to move. Explain the phenomenon.

10. Steam Boat

A boat can be propelled by means of a candle and metal tubing with two open ends (an example is shown in the picture). Explain how such a boat is propelled and optimize your design for maximum velocity.

Steam Boat

11. Water Ski

What is the minimum speed needed to pull an object attached to a rope over a water surface so that is does not sink. Investigate the relevant parameters experimentally and theoretically.

12. Fluid lens

Develop a fluid lens system with adjustable focus. Investigate the quality and possible applications of your system.

13. Balloon

Measure the change of the optical properties of the skin of a balloon during its inflation.

14. Earthquake

Suggest a mechanism that makes buildings resistant to earthquakes. Perform experiments and explain the results.

15. Blowpipe

Investigate the motion of a projectile inside a blowpipe. Determine the conditions for maximum exit velocity when blown by mouth.

16. Water Cascade

Arrange a corrugated drainage pipe, or similar, on an incline. Allow water to flow through the pipe and then carefully stop the flow. Investigate the behaviour of the system when water is dropped into the pipe.

Water Cascade

17. Ice Bulge

Fill a plastic tray with water. When frozen, under certain conditions, a bulge can appear on the surface. Investigate this phenomenon.

제19회(2006년)

Problems for the 19th IYPT: 5 - 11 July 2006 Bratislava, Slovakia
1. Froth

Investigate the nature of the decay in height of the 'froth' or 'foam' on a liquid. Under what conditions does the froth remain for the longest time?

2. Shades

If small non-transparent objects are illuminated with light, patterns in the shadows are observed. What information can be obtained about these objects using these patterns?

3. Duck's cone

If one looks at the wave pattern produced by a duck paddling across a pond, this reminds one of Mach's cone. On what parameters does the pattern depend?

4. Whispering Gallery

The Whispering Gallery at St Paul's Cathedral in London, for example, is famous for the fact that the construction of the circular gallery makes a whisper against its walls on one side of the gallery audible on the opposite side of the gallery. Investigate this phenomenon.

5. Probability

A coin is held above a horizontal surface. What initial conditions will ensure equal probability of heads and tails when the coin is dropped and has come to rest?

6. Wet cleaning

A wet rag is hard to drag when it is spread out and pulled across the floor. What does the resistive force depend on?

7. Airglider

A paper sheet is on a table. If one blows along the table the sheet begins to glide over it. Determine the flight characteristics of the paper.

8. Electrostatics

Propose and make a device for measuring the charge density on a plastic ruler after it has been rubbed with a cloth.

9. Sound and foam

Investigate the propagation of sound in foam.

10. Inverted pendulum

It is possible to stabilise an inverted pendulum. It is even possible to stabilise an inverted multiple pendulum (one pendulum on top of the other). Demonstrate the stabilisation and determine on which parameters this depends.

11. Singing tube

A tube open at both ends is mounted vertically. Use a flame to generate sound from the tube. Investigate the phenomenon.

12. Rolling magnets

Investigate the motion of a magnet as it rolls down an inclined plane.

13. Sound

Measure the speed of sound in liquids using light.

14. Cellular materials
16. Hardness

A steel ball falls onto a horizontal surface. If one places a sheet of paper onto the surface with a sheet of carbon paper on top of it, a round trace will be produced after the impact. Propose a hardness scale based on this method.

17. Magnetohydrodynamics

Investigate the behaviour of a stream of fluid when it strikes the surface of a sponge-like material.

15. Heat and temperature.

A tube passes steam from a container of boiling water into a saturated aqueous salt solution. Can it be heated by the steam to a temperature greater than #d0d0d0;">A shallow vessel contains a liquid. When an electric and magnetic field are applied, the liquid can start moving. Investigate this phenomenon and suggest a practical application.

제18회(2005년)

Problems for the 18th IYPT: 14 - 20 July 2005 Winterthur, Switzerland
1. Dragonfly

Propose a model of how a dragonfly flies. Investigate the major parameters and validate your model.

2. Two Balls

Two balls placed in contact on a tilted groove sometimes do not roll down. Explain the phenomenon and find the conditions under which it occurs.

3. Avalanche

Under what conditions may an avalanche occur? Investigate the phenomenon experimentally.

4. Hydraulic Jump

When a smooth column of water hits a horizontal plane, it flows out radially. At some radius its height suddenly rises. Investigate the nature of the phenomenon. What happens if a liquid more viscous than water is used?

5. Mirage

Create a mirage like a road or desert mirage in a laboratory and study its parameters.

6. Noise

When a droplet of water or other liquid falls on a hot surface, it produces a sound. On what parameters does the sound depend?

7. Bouncing Plug

A bathtub or sink is filled with water. Remove the plug and place a plastic ball over the plughole. As the water drains the ball starts to oscillate. Investigate the phenomenon.

8. Windcar

Construct a car which is propelled solely by wind energy. The car should be able to drive straight into the wind. Determine the efficiency of your car.

9. Sound in a Glass

Fill a glass with water. Put a tea-spoon of salt into the water and stir it. Explain the change of the sound produced by the clicking of the glass with the tea-spoon during the dissolving process.

10. Flow Rate

Combine powdered iron (iron filings) with a vegetable oil. Connect two containers with plastic tubing and allow the mixture to drain through the tube. Develop an external mechanism to control the flow rate of the mixture.

11. Water Droplets

If a stream of water droplets is directed at a small angle to the surface of water in a container, droplets may bounce off the surface and roll across it before merging with the body of water. In some cases the droplets rest on the surface for a significant length of time. They can even sink before merging. Investigate these phenomena.

12. Spinning Ball

Spin can be used to alter the flight of balls in sport. Investigate the motion of a spinning ball, for example a table-tennis or tennis ball, in order to determine the effect of the relevant parameters.

13. Hard Starch

A mixture of starch (e.g. corn flour or cornstarch) and a little water has some interesting properties. Investigate how its "viscosity" changes when stirred and account for this effect. Do any other common substances demonstrate this effect?

14. Einstein-de Haas

When you apply a vertical magnetic field to a metallic cylinder suspended by a string, it begins to rotate. Study this phenomena.

15. Optical Tunnelling

Take two glass prisms separated by a small gab. Investigate under what conditions light incident at angles greater than the critical angle is not totally internally reflected.

16. Funnel

Granular material is flowing out of a vessel through a funnel. Investigate if it is possible to increase the outflow by putting an "obstacle" above the outlet pipe.

17. Ocean Solaris

A transparent vessel is half-filled with saturated salt water solution and then fresh water is added with caution. A distinct boundary between these liquids is formed. Investigate its behaviour when the lower liquid is heated.

제17회(2004년)

Problems for the 17th IYPT: 24 June - 1 July 2004 Brisbane, Australia
1. Misty

Invent and construct a device that would allow the size of a droplet of a mist to be determined using a sound generator.

2. Stubborn Ice

Put a piece of ice (e.g. an ice cube) into a container filled with vegetable oil. Observe its motion and make a quantitative description of its dynamics.

3. Electric Pendulum

Use a thread to suspend a ball between the plates of a capacitor. When the plates are charged the ball will start to oscillate. What does the period of the oscillations depend on?

4. Dusty Blot

Describe and explain the dynamics of the patterns you observe when some dry dust (e.g. coffee powder or flour) is poured onto a water surface. Study the dependence of the observed phenomena on the relevant parameters.

5. Sea-shell

When you put a sea-shell to your ear you can hear ‘the sea’. Study the nature and the characteristics of the sound.

6. Seebeck Effect

Two long metal strips are bent into the form of an arc and are joined at both ends. One end is then heated. What are the conditions under which a magnetic needle placed between the strips shows maximum deviation?

7. Coin

Stand a coin on its edge upon a horizontal surface. Gently spin the coin and investigate the resulting motion as it settles.

8. Pebble Skipping

It is possible to throw a flat pebble in such a way that it can bounce across a water surface. What conditions must be satisfied for this phenomenon to occur?

9. Flow

Using a dc source, investigate how the resistance between two metallic wires dipped into flowing water (or water solution) depends upon the speed and direction of the flow.

10. Two Chimneys

Two chimneys stand on a box with one transparent side. Under each chimney there is a candle. A short period after the candles are lit one flame becomes unstable. Examine the case and present your own theory of what is happening.

11. String Telephone

How do the intensity of sound transmitted along a string telephone, and the quality of communication between the transmitter and receiver, depend upon the distance, tension in the line and other parameters? Design an optimal system.

12. Kundt’s Tube

In a ‘Kundt’s Tube’ type of experiment the standing waves produced can be made visible using a fine powder. A closer look at the experiment reveals that the regions of powder have a sub-structure. Investigate its nature.

13. Egg White

White light appears red when it is transmitted through a slice of boiled egg white. Investigate and explain this phenomenon. Find other similar examples.

14. Fountain

Construct a fountain with a 1m ‘head of water’. Optimise the other parameters of the fountain to gain the maximum jet height by varying the parameters of the tube and by using different water solutions.

15. Brazil Nut Effect

When a granular mixture is shaken the larger particles may end up above the smaller ones. Investigate and explain this phenomenon. Under what conditions can the opposite distribution be obtained?

16. Small Fields

Construct a device based upon a compass needle and use your device to measure the Earth’s magnetic field.

17. Didgeridoo

The ‘didgeridoo’ is a simple wind instrument traditionally made by the Australian aborigines from a hollowed-out log. It is, however, a remarkable instrument because of the wide variety of timbres that it produces. Investigate the nature of the sounds that can be produced and how they are formed.

제16회(2003년)

Problems for the 16th IYPT: 1-8 July 2003 Uppsala, Sweden
1. Motion of a kite

On windy days one can see kites flying in the wind. Often, one-string kites move on a stable track, which looks like a number

8. Why does a kite move in such a way? Are there other stable tracks?
2. Water drops

Investigate and explain the movement of raindrops on a window pane.

3. Transparent Film

If you cover printed text with a piece of transparent polyethylene film you can still easily read it. As you gradually lift up the film, the text becomes increasingly blurred and may even disappear. Study the properties of the film. On what parameters of the film is the phenomenon based?

4. Bright spots

Blow a soap bubble and allow it to rest on a liquid surface or a glass plate. When illuminated by sunlight, bright spots can be observed on the bubble. Investigate and explain the phenomenon.

5. Bubbles at an interface

Certain liquids can be layered one above the other with a sharp interface between them. If the surface tensions of the liquids are different, then an interesting phenomenon can be observed. Blow bubbles of different sizes into the lower liquid and observe their behaviour near the interface. Investigate and explain the phenomenon.

6. Freezing soft drinks

On opening a container of cold soft (carbonated) drink the liquid inside sometimes freezes. Study the relevant parameters and explain the phenomenon.

7. Oscillation box

Take a box and devide into a number of small cells with low walls. Distribute some small steel balls between the cells. When the box is made to made to oscillate vertically, the balls occasionally jump from one cell to another. Depending on the frequency and the amplitude of the oscillation, the distribution of the balls can become stable or unstable. Study this effect and use a model to explain it.

8. Heat engine

Construct a heat engine from a U-tube partially filled with water (or another liquid), where one arm of the tube is connected to a heated gas reservoir by a length of tubing, and the other arm is left open. Subsequently bringing the liquid out of equilibrium may cause it to oscillate. On what does the frequency of the oscillation depend on? Determine the pV diagram of the working gas.

9. Falling Chimney

When a tall chimney falls it sometimes breaks into two parts before it hits the ground. Investigate and explain this.

10. Tungsten lamp

The resistance of the tungsten filament in a light bulb shows a strong temperature dependence. Build and demonstrate a device based on this characteristics.

11. Light scattering

Construct an optical device for measuring the concentration of non-soluble material in aqueous colloid systems. Use your device to measure the fat content of milk.

12. Boiled egg

Construct a torsion viscometer. Use it to investigate and explain the differneces in the 'viscous' properties of hens' eggs that have been boiled to different extents.

13. Electro-osmosis

Develop a device that will drain wet sand, with the aid of an electrical voltage but without significant heating.

14. Rotating disk

Find the optimum way of throwing a 'frisbee' as far as possible. Explain your findings.

15. Vortices

Make a box that has a hole in its front wall and a membrane as its back wall. Hitting the membrane creates a vortex that propagates out from the hole. Investigate the phenomenon and explain what happens when two vortices interact.

16. Pot and ice

It is sometimes argued that to cool a pot effectively one should put ice above it. Estimate to what extent this is more effective than imore eice is put under the pot.

17. Prometheus problem

Describe and demonstrate the physical mechanism, based on friction, which allowed our ancestors to make fire. Estimate the time needed to make fire in this way.

제15회(2002년)

Problems for the 15th IYPT: 23-30 May 2002 Odessa, Ukraine
1. Heat engine

A tall glass cylinder is half-filled with hot water and topped up with cold water. A small ampoule, containing a few drops of ether or alcohol (and closed off by a rubber pipette cap), is then put in. Describe the phenomena occurring in the system. How does the motion of the ampoule change with time?

2. Spider's web

A spider's thread looks like a string of pearls. What is the reason for this? Make experiments to investigate the relevant parameters.

3. Flying colours

Why do flags flutter in the wind? Investigate experimentally the airflow pattern around a flag. Describe this behaviour.

4. Hazy

The colour of a distant forest appears not green, but hazy blue. What is the minimum distance at which this phenomenon is observed? How do weather conditions affect this? Is it possible that a forest can appear grey?

5. Pond skater

It is known that unwettable small bodies can float on water due to the surface tension force. Construct a floating raft based on this principle and determine its static and dynamic parameters.

6. Stop and start

Sometimes a flow of traffic can experience sudden stops and starts for no apparent reason. Build a physical model to explain why this occurs.

7. Ohm's Law for a liquid

It is said that electric current “flows”. Is this the only analogy between electric current and the flow of a liquid? Investigate theoretically and experimentally other analogies between these two.

8. Charged sand

Fine, well-dried quartz sand is poured out of a short thin tube into a conical metallic vessel connected to an electrometer. Investigate the behaviour of the sand stream as the vessel fills up. What changes if the stream is lit by a UV-lamp?

9. Chromatography

Put a drop of coloured liquid on a piece of absorbant paper. Describe quantitatively the observed phenomena.

10. Sound cart

Construct and demonstrate a device that can be propelled solely by sound. Investigate its properties.

11. Equilibrium

Fill a glass with water up to the point where a convex meniscus is formed. Place a table tennis ball on the surface of the water. Investigate and explain the stability of its equilibrium. Repeat your experiment with other liquids.

12. Electro-conductivity

How can you measure the electro-conductivity of salt solutions without using direct contact electrodes? Analyse the problem and demonstrate your device.

13. Spinning ball

A steel ball of diameter 2-3 cm is put on a horizontal plate. Invent and construct a device, which allows you to spin the ball at high angular velocity around a vertical axis. The device should have no mechanical contact with the ball.

14. Torn sail

Determine the dependence of the efficiency of a sail on its degree of perforation. What would be the effect of using a fishing net as a sail?

15. Pulsating air bubble

Trap an air bubble of radius 1-2 cm under an inverted watch glass beneath a water surface. Introduce alcohol into the bubble through a thin tube, controlling and adjusting the rate of flow until the bubble pulsates rhythmically. Study the phenomenon and explain your observations.

16. Elastic pendulum

Study and describe the behaviour of a pendulum where the bob is connected to a spring or an elastic cord rather than to a stiff rod.

17. Bottle battle

Take two opened glass bottles of cola and knock one against the other. After a short while, the cola spurts out of one of the bottles. Investigate and explain the phenomenon.