Phase — Science definition

Defined in 2 courses:

Where it is taught

In use

A phase is simply the name for how much of the sunlit half is turned toward us on a given night.

Earth, Moon & Sun: Moon Phases

Questions using phase

Problem 1

Within one phase, energy input can increase average motionWithin one phase, energy input can increase average motionCooler sampleWarmer same-phase sampleSame substance and particle count; longer arrows show faster average motion.Particles do not become larger when this sample warms.
Both panels represent the same number and kind of particles in one phase. The warmer panel uses longer motion arrows to show a higher average kinetic energy in this introductory model. The arrows are not forces and the circles do not expand. Actual particle motions vary; equal arrow styles are a drawing simplification rather than a claim that all particles share one speed.
For this unit’s illustrated case, what should change and what should stay the same in a particle drawing of this same-phase warming?
Answer and explanation

Motion patterns/average kinetic energy can change, while particle identity, count and size stay the same. This comparison is not a phase-change plateau.

Within a phase, a rising temperature can track increasing average particle kinetic energy. During a phase change, energy can change the arrangement instead; that requires a different model and a different reading of the curve.

Motion patterns/average kinetic energy can change, while particle identity, count and size stay the same. This comparison is not a phase-change plateau.

Response criteria

  • Use the named labels, directions or supplied quantities accurately.
  • Connect the visual evidence to the scientific mechanism or calculation.
  • State the relevant model conditions or limitation.

Problem 2

Which phase comes right after a new moon?
  1. Waxing crescent
  2. Full moon
  3. Waning gibbous
  4. Third quarter
Answer and explanation

Waxing crescent

Right after new moon, a thin sliver of light begins to grow — that's the waxing crescent.

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