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#thermal energy

3 public questions tagged with this topic.

How much heat is required to raise the temperature of 0.6 kg of silver from 20^circ C to 50^circ C ? (Specific heat of s

**Cyclic work** equals area inside loop, for rectangular cycle P₁V₁→P₂V₁→P₂V₂→P₁V₂→P₁V₁, W = (P₂-P₁)(V₂-V₁), heat absorbed and rejected during different legs, net work output for heat engine, input for refrigerator. Δ Q = m s Δ T . m = 0.6 , s = 236.1 , Δ T = 50 - 20 = 30 . Δ Q = 0.6 × 236.1 × 30 = 4249.8 J ≈ 4250 J . Using first law ΔU = Q - W, W = ∫ P dV, isobaric W = P ΔV, isothermal W = n R T ln(V₂/V₁), adiabatic P V^γ = const and η = 1 - T_c/T_h,

Ref: NCERT > Physics Book > Thermodynamics > Cyclic Processes and Reversibility Concepts

Which of the following correctly describes the concept of heat?

**First law applications** for isobaric W = P ΔV, Q = n C_p ΔT, ΔU = n C_v ΔT, for isothermal ideal gas ΔU=0 Q=W=n R T ln(V₂/V₁), for adiabatic Q=0 W= -ΔU = (P₁V₁ - P₂V₂)/(γ-1), for isochoric W=0 ΔU=Q=n C_v ΔT, enabling calculation of Q,W,ΔU for any process. Heat is energy transferred due to a temperature difference, not a stored property or work form. Option B is correct. Using first law ΔU = Q - W, W = ∫ P dV, isobaric W = P ΔV, isothermal W = n R T ln(V₂/V₁), adiabatic P V^γ = const and η = 1 -

Ref: NCERT > Physics Book > Thermodynamics > First Law of Thermodynamics Applications

What is the heat required to raise the temperature of 0.5kg of copper from 30∘C to 80∘C? (Specific heat of copper = 386J

Given: m = 0.5kg, ΔT = 80−30 = 50∘C, s = 386Jkg−1K−1. Q = msΔT = 0.5×386×50 = 9650J = 9.65kJ. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 9.65 kJ. This satisfies dimensional consistency and physical conditions given, so option B is scientifically correct.

Ref: NCERT Class 11 Physics, Chapter 11: Thermal Properties – Calorimetry.