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PhysicsHeat & ThermoThermal ExpansionMedium2 minQB

PhysicsMediumsingle choice

Passage / Comprehension

A solid of mass $0.10$ kg is heated by a constant $200$ W source. The temperature-versus-heat graph has the same shape as Figure 1.24: a rising segment OA (from $- 2 0^{\circ}$ C to $0^{\circ}$ C) taking $21$ s, a flat segment AB (melting) taking $167$ s, a rising segment BC ( $0$ to $10 0^{\circ}$ C) taking $210$ s, a flat segment CD (boiling) taking $1130$ s, then DE. The graph is schematic, not to scale.

Which option correctly gives $c_{so l i d}$ (J $k g^{- 1}$ $K^{- 1}$ ), $L_{f}$ (J $k g^{- 1}$ ), $L_{v} / L_{f}$ (one decimal place), and $c_{l i q u i d} / c_{so l i d}$ ?

Options:

Answer:

Solution:

(a) $200 \times 21 = 0.10 c \times 20 \Rightarrow c = 2100$ . (b) $200 \times 167 = 0.10 L_{f} \Rightarrow L_{f} = 3.34 \times 1 0^{5} J / kg$ . (c) times are proportional to heat, $1130/167 = 6.8$ . (d) $c_{liq} / c_{solid} = \frac{210/100}{21/20} = 2.0$ . Therefore option B.

Subject:PhysicsTopic:Heat & ThermoSubtopic:Thermal Expansion

⏱ 2mℹ️ Source: QB

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