Specific heat capacity as a material property · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Why water warms slowly

Science · Energy · ages 15-16
Name ______________________   Date ____________

  1. Equal masses of water and steel start at the same temperature and absorb the same energy without changing state. Water has the higher specific heat capacity. Which ends hotter?

    • The steel ends hotter
    • The water ends hotter
    • Both end at the same temperature

  2. What does the specific heat capacity of a material tell you?

    • The energy lost each second by one kilogram cooling in a draught
    • The energy needed to warm one kilogram by one degree Celsius
    • The energy needed to melt one kilogram at its melting temperature

  3. Which stage needs a latent-heat calculation instead of Q = mcΔT?

    • A solid warming below its melting temperature
    • A liquid warming below its boiling temperature
    • A pure solid melting at constant temperature

  4. A 3 kg block with c = 400 J/(kg°C) absorbs 6000 J without changing state. What is its temperature rise in °C?

    Answer: ______________

  5. A 2 kg block has c = 500 J/(kg°C) and warms by 10°C without changing state. How much energy does it absorb?

    • 1000 joules
    • 100000 joules
    • 10000 joules

  6. Two safe liquid coolants work over the same temperature range. Equal masses must absorb equal energy with as little temperature rise as possible. Which property helps?

    • A lower specific heat capacity
    • A higher specific heat capacity
    • An equal capacity but a lower boiling point

  7. A sample with c = 800 J/(kg°C) absorbs 4800 J and warms by 12°C without changing state. What is its mass?

    • 0.05 kg
    • 5.00 kg
    • 0.50 kg

  8. A 0.5 kg sample absorbs 9000 J and warms by 30°C without changing state. What is its specific heat capacity?

    • 600 J/(kg°C)
    • 150 J/(kg°C)
    • 6000 J/(kg°C)
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Answer key

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Why water warms slowly W1-mt_mXC9IKom3P-s1

  1. The steel ends hotter · Steel has the smaller c, so it has the larger temperature rise. Equal starting temperatures mean it also ends hotter.
  2. The energy needed to warm one kilogram by one degree Celsius · Specific heat capacity gives the energy needed per kilogram for each degree Celsius of temperature rise.
  3. A pure solid melting at constant temperature · Melting changes the state without a temperature rise under these conditions. The separate warming stages use Q = mcΔT.
  4. 5 · ΔT = Q/(mc) = 6000/(3 x 400) = 5°C.
  5. 10000 joules · Q = mcΔT = 2 x 500 x 10 = 10000 J.
  6. A higher specific heat capacity · For equal mass and absorbed energy, a higher c gives a smaller temperature rise. Other coolant requirements still matter.
  7. 0.50 kg · m = Q/(cΔT) = 4800/(800 x 12) = 0.50 kg.
  8. 600 J/(kg°C) · c = Q/(mΔT) = 9000/(0.5 x 30) = 600 J/(kg°C).
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