A 2 kg metal block is heated from 2 0 ∘ C to 6 0 ∘ C at 1 0 5 Pa. The linear expansion coefficient is 12 × 1 0 − 6 per °C, the specific heat is 900 J k g − 1 K − 1 and the density is 8000 kg m − 3 . Then:

Q = 2 × 900 × 40 = 72 kJ (A). V = 8000 2 = 2.5 × 1 0 − 4 m 3 and Δ V = 3 α Δ T V = 3.6 × 1 0 − 7 m 3 . W = 1 0 5 × 3.6 × 1 0 − 7 = 0.036 J (B). Fraction = 72000 0.036 = 5 × 1 0 − 7 (C). Δ U = Q − W ≈ 72 kJ (D). All four are correct.

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Physics - Heat & Thermo Question with Solution | TestHub

PhysicsHeat & ThermoThermodynamics Laws & Specific Heats of GasesHard2 minQB

PhysicsHardmultiple choice

A 2 kg metal block is heated from $2 0^{\circ}$ C to $6 0^{\circ}$ C at $1 0^{5}$ Pa. The linear expansion coefficient is $12 \times 1 0^{- 6}$ per °C, the specific heat is 900 J $k g^{- 1}$ $K^{- 1}$ and the density is 8000 kg $m^{- 3}$ . Then:

Options:(select one or more)

Answer:

A, B, C, D

Solution:

$Q = 2 \times 900 \times 40 = 72$ kJ (A). $V = \frac{2}{8000} = 2.5 \times 1 0^{- 4}$ $m^{3}$ and $Δ V = 3 α Δ T V = 3.6 \times 1 0^{- 7}$ $m^{3}$ . $W = 1 0^{5} \times 3.6 \times 1 0^{- 7} = 0.036$ J (B). Fraction = $\frac{0.036}{72000} = 5 \times 1 0^{- 7}$ (C). $Δ U = Q - W \approx 72$ kJ (D). All four are correct.

Subject:PhysicsTopic:Heat & ThermoSubtopic:Thermodynamics Laws & Specific Heats of Gases

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