Physics, worth exploring.

Two sliding blocks reach the same velocity. Will they stick or immediately slip again?

The camera missed the instant of the pulse. Can you reconstruct it from two frames and predict the third?

A star loses energy on every orbit. Will its next circuit take more time or less?

Use areas on an atmospheric temperature graph to find how much of a falling ice pellet refreezes, then calculate the small temperature lag of liquid water.

Find how much heat flows between adjacent junctions of an infinite copper lattice, then predict what happens when the wire joining them is cut.

Find the temperature profile of a laser-heated disc, then use optical paths to show how its varying refractive index focuses light even while its faces remain flat.

Find the greatest fraction of absorbed starlight that an ideal day and night heat engine can convert into captured wind power, while both hemispheres radiate to space.

Use conduction, latent heat and mass conservation to find how quickly lake ice grows, why its final thickness is finite, and why the water remains stably layered.

Find the maximum payload and the heating power needed for hovering by combining buoyancy with conduction, convection and net radiation.

Find the outlet temperatures of two opposite-flowing streams and explain how their outlet order can reverse while local heat flow remains from warmer to cooler fluid.

Build a one-layer radiation model of Earth, count reflected sunlight, and find how surface and atmospheric temperatures respond to changing infrared emissivity.