Question

If the working tool can not rest on a surface and normally used with one hand, its weight should be limited to:

• A. 4 kg
• B. 3 kg
• C. 2 kg
• D. 1 kg

Hint:

For optimal handheld tool design, keep the weight as low as possible (under 2 kg) and ensure the center of gravity is aligned close to the user's hand to reduce strain on the wrist.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Ergonomics in agricultural tool design aims to maximize worker comfort, productivity, and safety while minimizing muscle fatigue and musculoskeletal disorders (MSDs).
When designing handheld agricultural tools (like sickles, pruners, and weeders), limiting tool weight is critical to prevent fatigue.

Step 2: Detailed Explanation:
Holding a tool without support requires continuous, static muscular contraction of the hand, arm, and shoulder muscles.
If the tool is operated with a single hand and cannot rest on any working surface, the force needed to hold it upright accelerates muscle fatigue.
Ergonomic guidelines and international standards (like ISO standards for hand tool design) state:
1. The maximum weight for a tool held and operated continuously with one hand should not exceed $2.0\text{ kg}$ (and ideally should be less than $1.2\text{ kg}$ for prolonged use).
2. Tools heavier than $2\text{ kg}$ require two hands to operate safely, or must have external physical supports (like shoulder straps or rest surfaces) to redistribute the load.
Designing tools within this $2\text{ kg}$ limit significantly reduces the risk of repetitive strain injuries and boosts overall agricultural labor efficiency.

Step 3: Final Answer:
The weight of a single-handed, unsupported tool should be limited to $2\text{ kg}$.