Problems for the 2011 US Invitational YPT

USAYPT Members have access to "Guides" that the International Coaches
produce for each of these problems. The Guides are introductions to the
problems in both theory and experiment for beginning teachers.

The Guides cannot be shared with students (see the
Requirements and Guidelines for Professional Conduct).
Members must complete the security acknowledgement
statement in order to obtain a password to the guide web
pages. Contact the Secretary, USAYPT to start this process.

 

1. Domino Wave: Balance numerous domino tiles on a table or floor with their long axis vertical with horizontal spaces that can be varied. When the first tile is knocked over a domino wave occurs. Predict and measure the speed of this wave and its dependence on various parameters.

2. Salt Water Oscillator:  Pour fresh water into a tall container. Place a cup with a hole in its bottom surface on top of the fresh water. Prepare a solution of salt water and add some food coloring. Pour this solution into the cup on top of the fresh water and simultaneously push the cup down into the fresh water. Observe the on-again and off-again flow of salt water into the fresh water. Predict the frequency of these oscillations from first principles, and compare to experiment. Investigate sizes of holes, salt concentrations, and other liquids.

3. Magic Motor: Construct a DC motor without a commutator, using a single battery, a single permanent magnet, and a single loop of wire. Predict the frequency of rotation of this motor from first principles and compare to experiment.

4. Boiling Water: Some people say it is important to put a lid on the pot when you want to boil water for tea to save energy and time. Investigate this phenomenon and decide whether this hypothesis is true.