Internal Energy, Absolute Zero and the Kelvin Scale · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Inside heat: particles and kelvin

Science · Energy · ages 16-17
Name ______________________   Date ____________

  1. A block warms by 10 degrees Celsius. By how many kelvin did it warm?

    Answer: ______________

  2. Room temperature is 25 degrees Celsius. What is it in kelvin?

    Answer: ______________

  3. Which energy belongs to internal energy?

    • Random motion and bonds of the particles
    • Motion of the whole object
    • Energy of the container walls

  4. What is absolute zero?

    • Where water freezes
    • Where random kinetic energy is as low as it can go
    • Where objects stop existing

  5. Ice melts at 0 C with no temperature change. Which store of internal energy grows?

    • Potential energy of the molecules
    • Kinetic energy of the whole block
    • Nuclear energy of the atoms
    • Light energy escaping away

  6. Ice melts at 0 degrees. What changes inside?

    • Kinetic energy rises while potential drops
    • Both stay exactly fixed
    • Potential energy rises while kinetic stays flat

  7. Room temperature is 25 degrees Celsius. Give it in kelvin.

    Answer: ______________

  8. A speeding cold football has huge kinetic energy, so its internal energy is huge too. True or false?

    Circle one:   True   False

  9. Two cups warm by 5 C and 15 C. How do their kelvin rises compare?

    • 5 K and 15 K
    • Both 10 K
    • 278 K and 288 K

  10. A pupil says boiling water holds extra internal energy only because molecules move faster. What is missing?

    • Temperature is unrelated to energy
    • Faster molecules weigh more
    • Potential energy of bonds also counts
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Answer key

For grown-ups. Fold this page away before handing over the rest.

Inside heat: particles and kelvin W1-mt_n4Ku8ZDy1U-s1

  1. 10 · A Celsius degree matches a kelvin in size, so a rise of 10 C is a rise of 10 K.
  2. 298 · Add 273: 25 + 273 = 298 K.
  3. Random motion and bonds of the particles · Internal energy counts only the particles' own jiggling and bonds.
  4. Where random kinetic energy is as low as it can go · It is the floor of random motion, where the kelvin scale starts.
  5. Potential energy of the molecules · The temperature holds steady, so the input loosens bonds instead of speeding molecules.
  6. Potential energy rises while kinetic stays flat · Heat breaks bonds at fixed temperature, raising the potential part.
  7. 298 · Add 273: 25 plus 273 is 298 K.
  8. False · Bulk motion belongs to the whole object, while internal energy counts only the particles' own jiggling and bonds.
  9. 5 K and 15 K · Rises match exactly across scales; only the zero points differ.
  10. Potential energy of bonds also counts · Internal energy totals kinetic plus potential over the particles.
Worksheet · LightMySky