Physics 9702 · AS & A Level · Specific heat capacity and specific latent heat

Specific heat capacity and specific latent heat — practice question

At $0^{\circ}\text{C}$, the thermistor has a resistance of $3840\,\Omega$. When the temperature is $100^{\circ}\text{C}$, its resistance drops to $190\,\Omega$. If the thermistor is placed in water held at one fixed temperature, the resistance measured is $2300\,\Omega$.
(a(i))[2]

Assuming that thermistor resistance changes linearly with temperature, calculate the temperature of the water.

(a(ii))[3]

On the thermodynamic scale of temperature, the water has a temperature of $286\,\text{K}$. Using your understanding of what the thermodynamic temperature scale means, comment on your answer in (i).

(b)[4]

A polystyrene cup holds $95\,\text{g}$ of water at $28^{\circ}\text{C}$. A cube of ice with mass $12\,\text{g}$ is added to the water. At the beginning, the ice is at $0^{\circ}\text{C}$. The water, which has specific heat capacity $4.2 \times 10^3\,\text{J kg}^{-1}\text{K}^{-1}$, is stirred until every part of the ice has melted. Assume that the cup has negligible mass and that there is no heat transfer with the surroundings. Calculate the final temperature of the water. The specific latent heat of fusion of ice is $3.3 \times 10^5\,\text{J kg}^{-1}$.

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This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: temperature change proportional to resistance change calculation

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