GATE — Agricultural Engineering (AG) · India · IITs and IISc on rotation (2026: IIT Guwahati)
Original practice questions written to the published syllabus · not past papersDesigning machines around the people who use them, and measuring the noise, vibration and work load they face.
In the exams: GATE AG Section 3 (ergonomics asked in all 8 papers 2019–26); ICAR AIEEA-PG Unit V; ICAR AICE subject 39 Unit 5; NCEES PE health and safety
GATE — Agricultural Engineering (AG)
Human engineering and safety in the Farm Power section: numerical questions on adding decibel levels, change of level with distance or number of sources, noise dose, vibration transmissibility, natural frequency and damping ratio from logarithmic decrement, rms acceleration, anthropometric percentiles from mean and SD, and energy expenditure from oxygen uptake or heart rate. NAT answers are sensitive to using 10 log versus 20 log and rms versus peak.
How our questions for GATE spread across the units of Human Engineering, Ergonomics & Safety. Difficulty: 8 easy, 18 medium, 11 hard.
| Vibration: transmissibility and damping | 11 | |
| Noise: decibels and exposure | 9 | |
| Work physiology: energy expenditure, heart rate and oxygen uptake | 6 | |
| Anthropometry | 5 | |
| Design of controls and seats | 3 | |
| Dust and thermal stress | 1 | |
| Safety standards and ROPS | 1 | |
| Tools designed for women workers | 1 |
Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.
The stature of a group of farm workers is normally distributed with mean 1640 mm and standard deviation 58 mm. The 95th percentile stature is closest to
D. 1735 mm
X95 = mean + 1.645 × SD = 1640 + 1.645 × 58 = 1735.4 mm. Mean + 1 SD (1698 mm) is only the 84th percentile; 1545 mm is the 5th percentile; z = 1.96 (1754 mm) is the 97.5th percentile, a common slip from two-sided confidence intervals.
A tractor operator must identify the hydraulic lift lever by touch without looking at it. The most suitable coding method is
C. shape coding
Shape (and texture or size) can be felt through gloves without looking. Colour and labels need vision and good lighting.
Increasing the control-response (C/R) ratio of a control, other things equal,
D. improves fine adjustment but slows gross movement to a target
A high C/R ratio means large control movement for small response: slow travel, precise final positioning. A low ratio gives fast travel but overshoot. Total time is minimised at an intermediate ratio.
Using the regression EE (kJ/min) = 0.159 × HR − 8.72, the energy expenditure of a woman worker whose average working heart rate is 130 beats/min is
C. 11.95 kJ/min
EE = 0.159 × 130 − 8.72 = 20.67 − 8.72 = 11.95 kJ/min. Omitting the constant gives 20.67; adding it gives 29.39; 2.85 is the kcal/min value mislabelled as kJ/min.
Further reading: Varghese et al. regression used in Indian farm ergonomics
A pedal-operated thresher is driven with a mechanical power output of 60 W while the operator's energy expenditure is 21 kJ/min. The gross mechanical efficiency is about
A. 17.1%
21 kJ/min = 21 000/60 = 350 W; η = 60/350 = 17.1%. 28.6% divides 60 W by 210 instead of 350 (a slip in converting kJ/min to W); 2.9% is 60/21 = 2.86 with the units ignored; 4.8% divides 60 by 21 × 60 = 1260, multiplying by 60 instead of dividing. A value near 17% is plausible for pedalling.
Three identical pumps each produce 90 dB at the operator's position. With all three running, the level is about
A. 94.8 dB
L = 90 + 10 log 3 = 94.77 dB. 93 dB is the two-source answer; 270 is arithmetic addition; 99.5 wrongly uses 20 log 3.
Ten identical chaff cutters in a shed each produce 84 dB at a point. With all ten running, the level is
D. 94 dB
L = 84 + 10 log 10 = 94 dB. 87 is the two-source result; 104 uses 20 log 10; 840 is arithmetic addition.
A seat must isolate (transmit less than the input of) vibration at 5 Hz. Its natural frequency must be below about
C. 3.54 Hz
Isolation needs r = f/fn > √2, so fn < 5/√2 = 3.54 Hz. 5 Hz would be resonance; 7.07 Hz inverts the ratio; 2.5 Hz is sufficient but is not the limit.
A tractor driver is exposed to a frequency-weighted rms acceleration of 0.8 m/s² for 5 hours a day. The daily exposure A(8) is about
B. 0.63 m/s²
A(8) = aw √(T/8) = 0.8 × √(5/8) = 0.632 m/s². Linear scaling gives 0.50; ignoring duration gives 0.80; inverting the ratio gives 1.01.
A seat with stiffness 40000 N/m, effective mass 90 kg and damping coefficient 760 N·s/m has a damping ratio of about
B. 0.20
cc = 2√(km) = 2√(40000 × 90) = 3795 N·s/m; ζ = c/cc = 760/3795 = 0.200. Forgetting the factor 2 gives 0.40; the other options are formula slips. Putting the 2 inside the root, √(2km) = 2683, gives 0.28, and using 4√(km) gives 0.10.
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