Idea 9of 9Builds onThe price per degreeThe thermometer stops
Two bills, one graph
Ice at zero to steam. What is the bill?
Today you'll discover
- how to read a whole heating story off one line
- which piece each equation prices
- what halving the mass does to every piece
Think firstIce at 0 °C, heated to steam at 100 °C
Melting, warming the water, boiling. Which piece costs the most energy?
Decide first, then press Next. Read each piece's length as its bill.
A complete heating curve for a kilogram of water: a flat piece at zero, a slope to one hundred, a long flat piece at one hundred. After a prediction, each piece is labelled with its energy, then the curve is redrawn for half a kilogram, every piece half as long, then named. The last step asks what a steeper slope means.
See the whole ideathe big idea and the key word, in one place
The big idea
A heating curve draws both: slopes for degrees, flats for state.
Compare themHalve the mass and every piece halves. Change the substance and the slopes and flats change separately: c sets the slopes, L sets the flats.
Key word
- heating curve
- a graph of temperature against energy added (or time at constant power) as a substance warms and changes state
About this modelDrawn to scale: boiling costs about seven times what melting costs, per kilogram.
Drawn to scale: boiling costs about seven times what melting costs, per kilogram.
Ready to use it?
- Read a heating curve: name the equation for each piece and compare their energies.