CayPT 2019 New



Registration for CaYPT 2019 is now closed.

How do I prepare for CaYPT?

Please see the CaYPT 2019 Schedule for the plan of the day. In addition, familiarize yourself with the map of the location as well as the scoresheets that will be used in the judging process.

The following are the selected problems for CaYPT 2019. It is suggested that your team attempt all of these problems as soon as possible.


  1. A. Undertone Sound
    Allow a tuning fork or another simple oscillator to vibrate against a sheet of paper with a weak contact between them. The frequency of the resulting sound can have a lower frequency than the tuning fork’s fundamental frequency. Investigate this phenomenon.
  1. B. Funnel and Ball
    A light ball (e.g. ping-pong ball) can be picked up with a funnel by blowing air through it. Explain the phenomenon and investigate the relevant parameters.
  1. C. Filling Up a Bottle
    When a vertical water jet enters a bottle, sound may be produced, and, as the bottle is filled up, the properties of the sound may change. Investigate how relevant parameters of the system such as speed and dimensions of the jet, size and shape of the bottle or water temperature affect the sound.
  1. D. Hurricane Balls
    Two steel balls that are joined together can be spun at incredibly high frequency by first spinning them by hand and then blowing on them through a tube, e.g. a drinking straw. Explain and investigate this phenomenon.
  1. E. Loud Voices
    A simple cone-shaped or horn-shaped object can be used to optimise the transfer of the human voice to a remote listener. Investigate how the resulting acoustic output depends on relevant parameters such as the shape, size, and material of the cone.
  1. F. Suspended Water Wheel
    Carefully place a light object, such as a Styrofoam disk, near the edge of a water jet aiming upwards. Under certain conditions, the object will start to spin while being suspended. Investigate this phenomenon and its stability to external perturbations.
  1. G. Looping Pendulum
    Connect two loads, one heavy and one light, with a string over a horizontal rod and lift up the heavy load by pulling down the light one. Release the light load and it will sweep around the rod, keeping the heavy load from falling to the ground. Investigate this phenomenon.
  1. H. Newton’s Cradle
    The oscillations of a Newton’s cradle will gradually decay until the spheres come to rest. Investigate how the rate of decay of a Newton’s cradle depends on relevant parameters such as the number, material, and alignment of the spheres.
  1. I. Sinking Bubbles 
    When a container of liquid (e.g. water) oscillates vertically, it is possible that bubbles in the liquid move downwards instead of rising. Investigate this phenomenon.
  1. J. Popsicle Chain Reaction
    Wooden Popsicle sticks can be joined together by slightly bending each of them so that they interlock in a so-called “cobra weave” chain. When such a chain has one of its ends released, the sticks rapidly dislodge, and a wave front travels along the chain. Investigate the phenomenon.


Use these to further aid your preparation. Good luck!