About this archive

The aim of this prototype website is to explore the capabilities of state-of-the-art large language models (LLMs) for solving demanding physics problems. Original problem texts and solutions by human experts are presented along with LLM-generated summaries, solutions and self-assessments.

The archive currently includes problems from the 2025-2026 NBPhO competitions, with potential to expand to earlier years and other types of competitions in the future.

Each problem comes with up to five companion views accessible from any problem page:

A word of caution

Claude's summaries, solutions and self-assessments are generated by a large language model and have not been reviewed by human physics experts. Based on spot-checks against official solutions, these are generally sound and pedagogically useful, suitable as a study aid, but may still contain errors. Treat them as an informed starting point, not as an authoritative answer key.


This prototype website was created by Mihkel Kree using Claude.

NBPhO 2026 Claude's self-scoring total: 48.5 / 54.0 ≈ 89.8%

1. Moving Lens 6 pts
Problem by Eppu Leinonen
Optics · Geometric optics, Thin-lens imaging, Geometric construction

Reconstruct the unseen circular path of a moving thin lens, and the direction of its plane, from the closed image curves it traces of two fixed object points.

2. Lissajous Bridge 6 pts
Problem by Jaan Kalda
Electricity · AC circuits, Phasors, AC bridge, Lissajous figures

Find the on-screen amplitude of the xx-channel signal at the slider position that collapses the oscilloscope Lissajous trace into a line segment.

3. Kirill on a Swing 8 pts
Problem by Kaarel Hänni
Mechanics · Pendulum dynamics, Parametric resonance, Angular momentum conservation

A child on a rigid-rod swing parametrically pumps the amplitude by squatting at turning points and standing up at the bottom; count the stand-ups required to go over the top.

4. Rod and Bead 8 pts
Problem by Eero Ristolainen, Jaan Kalda
Mechanics · rotating reference frames, linear forced oscillators, parametric stability, charged-particle motion in rotating fields

A bead slides on a frictionless rod that rotates about a horizontal axis; identify the bounded circular trajectory generated by gravity, stabilise it with a Hooke spring, and reverse-engineer the parameters of a rotating electric field from the resulting rosette pattern.

5. Saturation Pressure of Water Exp 8 pts
Problem by Eero Uustalu
Thermodynamics · Vapour pressure, Phase equilibrium, Hydrostatics, Manometry

Determine the saturated vapour pressure of water at room temperature using a long dodecane-filled tube and a syringe, exploiting the immiscibility of dodecane and water and the hydrostatic balance of the liquid columns.

6. Pull-Up Bar Rope 5 pts
Problem by Jaan Kalda
Mechanics · Kinematics, Constraints, Statics

A rope pulled at constant rate over a horizontal bar drags a weight across a frictionless floor; find its speed, acceleration, and the angle at which it lifts off.

7. Water Hose 5 pts
Problem by Ralf Robert Paabo
Mechanics · Fluid dynamics, Dimensional analysis, Energy balance

Derive the Reynolds number from drag-force scaling, classify the flow in a garden hose, and compute how a nozzle changes the flow rate and the cleaning pressure.

8. Jet Sound 8 pts
Problem by Teo Kai Wen, Jaan Kalda
Waves · Doppler effect, Sound propagation, Supersonic flow

Decode a supersonic flyby spectrogram to extract the Mach number and closest-approach distance from the Doppler asymptotes and the sonic-boom delay.

9. CO₂ Fire Extinguisher 8 pts
Problem by Jaan Kalda
Thermodynamics · Phase transitions, isentropic flow, Clausius-Clapeyron

Use a TTss diagram of CO₂ to find the dry-ice fraction in the exhaust of a fire extinguisher for two cylinder orientations, then derive the condition under which adiabatic expansion of saturated vapour spontaneously condenses.

10. Ball Magnet Exp 10 pts
Problem by Jaan Kalda
Electromagnetism · Magnetostatics, Magnetic dipole, Geomagnetism, Paramagnetism

Using a ball-shaped neodymium magnet as a calibrated point dipole, locate its magnetisation axis, measure the strength of the Earth's magnetic field, and extract the magnetic susceptibility of a small titanium wire piece from the force on it in the magnet's inhomogeneous field.

NBPhO 2025 Claude's self-scoring total: 45.3 / 48.0 ≈ 94.4%

1. Flying Dumbbell 10 pts
Problem by Jaan Kalda
Mechanics · Elasticity, Oscillations, Collisions, Rigid-body rotation

Dynamics of a steel dumbbell in zero gravity — longitudinal oscillations and wall collisions at various angles of incidence.

2. Evaporation 7 pts
Problem by Jaan Kalda
Thermodynamics · Phase transitions, Diffusion, Heat transfer

Piston–cylinder equilibrium with saturated vapour, and derivation of the wet-bulb temperature of sweating skin in a sauna.

3. Nuclear Reactors 6 pts
Problem by Topi Lind
Modern Physics · Nuclear physics, Elastic collisions, Ideal gas

Neutron moderation in a thermal reactor — speeds, temperatures, number of collisions to thermalise, and gas buildup in spent fuel rods.

4. Black Box Exp 12 pts
Problem by Eero Uustalu
Electricity · Circuit analysis, Diodes

Determine the internal circuit topology, resistor value, and diode opening voltages of an unknown black box containing three diodes and a resistor.

5. Throwing 6 pts
Problem by Eppu Leinonen
Mechanics · Kinematics, Projectile motion, Non-inertial frames

Minimum-speed projectile to intercept an accelerating drone, and graphical determination of speeds in a stone–ball intercept problem.

6. Birds 4 pts
Problem by Jaan Kalda
Mechanics · Statics, Buoyancy, Torque equilibrium

Find the maximum number of identical birds a floating square-cross-section beam can hold above water, given a specific one-bird tipping condition.

7. Charged Rod 6 pts
Problem by Jaan Kalda
Electromagnetism · Lorentz force, Rigid body dynamics

Rotation and translation of a uniformly charged rod in a homogeneous magnetic field, subject only to the Lorentz force.

8. Phase Spiral 9 pts
Problem by Taavet Kalda
Astrophysics · Galactic dynamics, Gravitational potential, Phase mixing

Infer the Milky Way's vertical gravitational potential and dark matter density from the phase-space winding spiral of nearby stars (after Antoja et al. 2018, Guo et al. 2024).

9. Hot Plate Exp 12 pts
Problem by Jaan Kalda
Thermodynamics · Thermal radiation, Heat transfer, Calorimetry

Measure emissivity of polished aluminium, the heat transfer coefficient to air, heat capacity of a metal plate, and thermal conductance of silicone rubber pads.