John heats 1 kg of soup from 25 °C to 70 °C for 15 minutes by a heater. How long does the same heater take to heat 1.5 kg of the same kind

Question

John heats 1 kg of soup from 25 °C to 70 °C for 15 minutes by a heater. How long does the same heater take to heat 1.5 kg of the same kind of soup from 20 °C to 80 °C? The energy output per unit time by the heater is constant.

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Minh Khuê 1 year 2021-09-01T22:47:52+00:00 1 Answers 1 views 0

Answers ( )

    0
    2021-09-01T22:49:49+00:00

    Answer:

    30 minutes

    Explanation:

    Energy per time is constant, so:

    E₁ / t₁ = E₂ / t₂

    m₁C₁ΔT₁ / t₁ = m₂C₂ΔT₂ / t₂

    (1 kg) C (70°C − 25°C) / 15 min = (1.5 kg) C (80°C − 20°C) / t

    (1 kg) (45°C) / 15 min = (1.5 kg) (60°C) / t

    3/min = 90 / t

    t = 30 min

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