Farm Machinery and Power Engineering- ICAR JRF/SRF 2024

• Quetelet Index (Body Mass Index - BMI):
• Formula:

• Calculation:
• Worker's Weight = $81\text{ kg}$
• Worker's Height = $180\text{ cm} = 1.80\text{ m}$

• Note: The resting metabolic rate (95 W), work demand (25 W), and steady-state energy expenditure (210 W) are physiological workload parameters, but the Quetelet Index is strictly an anthropometric measure.
• Conclusion: 25.00 (Option 3).

Correct option: (3) 25.00

• Solar Hour Angle ($\omega$):
• Definition: The angular measure of time, representing the sun's position east or west of the local meridian. The Earth rotates $360^\circ$ in 24 hours, which corresponds to $15^\circ$ per hour.
• Formula:

• Calculation at 3:30 PM (15.5 hours):

• Sign Convention: The hour angle is negative before solar noon, zero at solar noon, and positive in the afternoon.
• Conclusion: 52.5° (Option 4).

Correct option: (4) 525°

• Cold Starting Fuel-Air Ratio in Carbureted Engines:
• Combustible Limits: The air-fuel mixture entering the cylinder must be within the combustible limits of $25:1$ (lean limit) and $8:1$ (rich limit) by weight.
• Fuel Vaporization Fraction: At low ambient temperatures during cold starting, only $10\%$ ($0.10$) of the delivered fuel vaporizes in the intake manifold.
• Calculation:
• For the leanest vaporized mixture that will ignite: $(A/F_v) = 25:1 \implies (F_v/A) = 1/25 = 0.04$.
• Since only $10\%$ of the supplied fuel $F_s$ vaporizes ($F_v = 0.10 F_s$), the supplied fuel-to-air ratio must be:

• Conclusion: Carburetor must supply a rich fuel-to-air ratio of 0.4:1 (Option 4).

Correct option: (4) 0494