These are the problems chosen for the New Zealand Young Physicist Tournament 2025. To be in contention for the national champions trophy, teams must be able to present their practical research into at least three problems at the Tournament in March 2025.

1. Invent Yourself: Paper Boomerang: Make a returning boomerang from a sheet of paper by folding and/or cutting. Investigate how its motion depends on relevant parameters.

2. Air Muscle: Place a balloon inside a cylindrical net (as is sometimes used to wrap garlic) and inflate it. The net will expand and shorten. Investigate the properties of such a “muscle”.

3.  Lato Lato: Attach a ball to each end of a string and connect the centre of the string to a pivot. When the pivot oscillates along the vertical direction, the balls start to collide and oscillate with increasing amplitude. Investigate the phenomenon.

4.  Climbing Magnets: Attach a rod assembled from cylindrical neodymium magnets horizontally to a vertical ferromagnetic rod. Limit the motion of the magnets to the vertical direction. When the
ferromagnetic rod is spun around its axis of symmetry, the magnetic rod begins to climb
up. Explain this phenomenon and investigate how the rate of climbing depends on relevant
parameters.

5.  Ruler Cannon: Two rulers are tightly held against each other. A round projectile (e.g. a plastic bottle cap or a ball) is inserted between them close to one of their ends. When extra force is exerted on the surface of the rulers, the projectile is ejected at a high speed. Investigate this effect and the parameters that affect ejection speed.

6.  Sound Versus Fire: A small flame can be put out by sound. Investigate the parameters of the flame and characteristics of the sound that determine whether the flame will be extinguished.

7. Water Bottle Rocket: Pump air into a plastic water bottle partially filled with water. Under certain conditions, the bottle is launched and flies into the air. Investigate how the acceleration during lift-off depends on relevant parameters.