Thermal physics
Melting, vaporization, condensation
Explore the heating curve of water: on sloped segments temperature rises as , while at melting and boiling the temperature stays flat because energy goes to the phase change . Vary supplied energy and mass to measure the plateau lengths.
Equipment
- Virtual ice–water–steam container with a temperature–energy graph
- Supplied-energy slider (0–100%)
- Water-mass slider (100–1000 g)
- Readout of the current heating stage
Procedure
Identify the curve segments
Drag the energy slider from 0 and read the stage readout: first 'warming ice', then the flat 'melting near 0 °C' plateau, then 'warming liquid water', the flat 'boiling near 100 °C' plateau, finally 'heating steam'. Note the boundary positions of each segment.
Verify the phase-change plateaus
Stop the slider mid-melting: energy keeps rising but temperature holds at 0 °C — the latent heat of fusion breaks crystal bonds instead of raising molecular kinetic energy. Likewise at 100 °C the vaporization plateau is much longer because is larger.
Change the mass and predict
Raise the mass from 500 g to 1000 g and watch the curve: every segment doubles in length since both and scale with mass. Predict the energy needed to boil away 300 g of water and check on the graph.