Subtopic: Steady state heat transfer in conduction, convection and radiation
Question Statement:
A cork slab of 100 mm thickness has one face at −12 °C and the other face at 21 °C. If the mean thermal conductivity (k) of the cork is 0.042 J m⁻¹ s⁻¹ K⁻¹, the rate of heat transfer (J s⁻¹) through one m² of the wall will be
Options:
(A) 13.9
(B) 9.3
(C) 5.0
(D) 2.5
Official Answer Key:
A
Step-by-Step Solution & Explanation
Steady conduction: q = kAΔT/L = 0.042×1×(21−(−12))/0.1 = 0.042×33/0.1 = 13.86 ≈ 13.9 W.
Appendix A — Consolidated Answer Table
Appendix B — Section-wise Weightage & Preparation Observations
Preparation observations
Engineering Mathematics (Section 1) and Farm Power (Section 3) together account for the largest share of marks in this paper — both need consistently strong footing, with Farm Power weighted heavily toward IC-engine thermodynamics, valve timing, governor behaviour, and tractor hydraulics/traction numericals.
Soil and Water Conservation Engineering (Section 4) draws heavily on fluid mechanics fundamentals (Reynolds number, pipe flow regime, hydrostatics) combined with hydrology (unit hydrographs, return period/probability, stream gauging) — practise both the conceptual and numerical sides together.
Irrigation and Drainage (Section 5) and Agricultural Process/Dairy & Food Engineering (Sections 6–7) questions in this paper are dominated by applied numericals (drain spacing, irrigation scheduling, psychrometry, size-reduction laws, heat transfer) rather than pure recall — formula fluency and unit-consistency are the main differentiators.
The paper's common-data and linked-answer question blocks (Q71–Q85) cluster around size-reduction laws, sprayer calibration, irrigation scheduling, contour bunding, groundwater heads, freeze-drying, and tractor traction — these are efficient topics to master since one concept unlocks two questions' marks.
A small number of questions in this set (flagged individually above) have data that is ambiguous or incomplete as transcribed from the source PDF (e.g. a missing wheelbase dimension, a possibly divergent integral, an under-specified governor problem); in an actual exam, cross-check such items against the official key rather than relying solely on a single derivation.
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