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Question #42141

Difficulty: 8/10 | 🟢 Free

The Question

A nuclear micro-reactor powers a heating system by converting mass into energy. The rate of mass defect in the reactor varies with time as dmdt=λt\frac{dm}{dt} = \lambda t, where λ=1.4×10−13 kg/s2\lambda = 1.4 \times 10^{-13} \text{ kg/s}^2. The reactor operates from t=0t = 0 to t=10 st = 10 \text{ s}. The entire energy released is used to heat a mixture of two liquids, A and B, kept in a perfectly insulated container. Liquid A has a mass of 1 kg1 \text{ kg} and a temperature-dependent specific heat capacity sA(T)=αT2s_A(T) = \alpha T^2, where α=0.01 J kg−1K−3\alpha = 0.01 \text{ J kg}^{-1} \text{K}^{-3}. Liquid B has a mass of 2 kg2 \text{ kg} and a specific heat capacity sB(T)=αT2s_B(T) = \alpha T^2. If the initial temperature of the mixture is 100 K100 \text{ K}, find the final temperature of the mixture. (Take the speed of light c=3×108 m/sc = 3 \times 10^8 \text{ m/s}).

Options

  • A.

    400 K400 \text{ K}

  • B.

    500 K500 \text{ K}

  • C.

    800 K800 \text{ K}

  • D.

    2200 K2200 \text{ K}

Check Your Answer

Correct Answer

Step-by-Step Solution

Explanation

How the Examiner Thinks

Multi-Concept_Bridge

Master problems that require linking physics and math concepts to solve complex competitive questions.

Concepts Behind This Question

Specific Heat Capacity of Phase Mixtures|Nuclear Fission Energy Balance

Why This Question Is Tricky

Common Mistakes

This problem tests the integration of variable power output (via a time-dependent mass defect rate) and the application of energy balance to a system with temperature-dependent specific heat.

A common trap is assuming Q=mCΔTQ = m C \Delta T using the initial specific heat, which bypasses the required thermodynamic integral ∫C(T)dT\int C(T) dT and leads to an incorrect final temperature of 2200 K2200 \text{ K}.

Furthermore, students often miscalculate the total energy by multiplying the final mass defect rate by time instead of integrating.

Quick Facts About This Question

Question Information

SubjectPhysics
ChapterThermal Properties of Matter - Class 11 Part 2
ConceptSpecific Heat Capacity of Phase Mixtures
Difficulty8
Cognitive Load7
Target Solve Time160 sec
AccessFree