Module 06 — Heat and Particles · quiz worth 15 pts
Three different ideas use everyday words that sound interchangeable. Separate them before doing any math.
Average translational kinetic energy per particle.
Energy stored across all the particles and interactions in the sample.
Energy crossing from a warmer system to a cooler one.
NIST's Kelvin reference explains the absolute-temperature scale. Use the course equations and 273.15 offset for the calculations here.
Which quantity can increase when you double the amount of boiling water while temperature stays the same?
Total internal energy. The larger sample has more particles.
Got it now? Scroll back up and re-read the section — it should land differently.
| Reference | Celsius | Fahrenheit | Kelvin |
|---|---|---|---|
| Absolute zero | −273.15 °C | −459.67 °F | 0 K |
| Water freezes | 0 °C | 32 °F | 273.15 K |
| Water boils | 100 °C | 212 °F | 373.15 K |
Temperature is proportional to the average translational kinetic energy of the particles in a substance. Two liters of boiling water and one liter of boiling water can have the same temperature because their particles have the same average kinetic energy. The larger sample has more total internal energy because it contains more particles. Heat is energy crossing a system boundary from higher temperature to lower temperature.
Kelvin is the SI temperature unit. Write K, not °K.
The Fahrenheit interval is 9/5 as large as the Celsius interval.
Subtract 32 before multiplying by 5/9.
Copy the value and unit. A bare 68 is not enough information.
For 68 °F, use the Fahrenheit-to-Celsius equation before converting to kelvins.
Temperature values need the 32 or 273.15 offset. Temperature differences do not: a change of 5 °C equals a change of 5 K.
At standard atmospheric pressure, water freezes near 0 °C, 32 °F, or 273.15 K and boils near 100 °C, 212 °F, or 373.15 K.
Write the direction above the work: °F → °C or °C → K.
Subtract 32 first, then divide by 1.8.
Add 273.15. Keep the answer in kelvins without a degree sign.
Is 5 °C a difference of 5 K?
Yes. The interval sizes match; only the zero points differ.
Got it now? Scroll back up and re-read the section — it should land differently.
ΔL and L₀ use the same length unit; α is in K⁻¹ or °C⁻¹; ΔT is in K or Celsius degrees.
Use the sign of ΔT. Cooling normally makes ΔL negative.
The equation is a chain of three multipliers.
α tells how strongly that material expands per degree.
A longer object changes more for the same material and temperature change.
Use final minus initial, not the final temperature by itself.
Got it now? Scroll back up and re-read the section — it should land differently.
How much longer does the beam become?
ΔL = 0.0012 m = 1.2 mm.
Absolute zero is 0 K, equal to −273.15 °C. It is the lower limit of thermodynamic temperature. A system at its lowest possible state has no thermal energy available to remove, but quantum systems can retain zero-point energy. The old ideal-gas extrapolation toward zero pressure or volume helped reveal this limit; real gases condense before reaching it.
Liquid water reaches its greatest density near 4 °C. Cooling below that point builds a more open hydrogen-bond structure, so the volume increases. Ice is less dense than liquid water and floats, insulating the water below. Water's high specific heat also lets oceans and lakes absorb large amounts of energy with smaller temperature changes than many land materials.
Temperature is an average per particle. Sample size changes total energy, not the temperature of otherwise identical samples.
A system stores internal energy. Heat names energy while it is being transferred because of a temperature difference.
Write 293 K, not 293 °K.
Expansion depends on Tfinal − Tinitial.
Work the unit or idea before choosing. Each explanation shows the check that matters.
