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PhysicsHeat & ThermoThermodynamics Laws & Specific Heats of GasesMedium2 minQB

PhysicsMediummultiple choice

A metal bar of 1 kg is heated at atmospheric pressure ( $P_{a t m} = 1 0^{5}$ N/ $m^{2}$ ) from $2 0^{\circ}$ C to $7 0^{\circ}$ C. The coefficient of linear expansion, the specific heat and the density of the metal are $20 \times 1 0^{- 6}$ per °C, 400 J/kg/°C and $1 0^{4}$ kg/ $m^{3}$ respectively. Choose the correct statement(s):

Options:(select one or more)

Answer:

A, C, D

Solution:

$Q = 1 \times 400 \times 50 = 20$ kJ (C). $Δ V = 3 α Δ T \cdot V = 3 \times 20 \times 1 0^{- 6} \times 50 \times 1 0^{- 4} = 3 \times 1 0^{- 7}$ $m^{3}$ . $W = 1 0^{5} \times 3 \times 1 0^{- 7} = 0.03$ J, fraction = $1.5 \times 1 0^{- 6}$ (A). $Δ U \approx Q$ (D). A, C, D.

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

⏱ 2mℹ️ Source: QB

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