A pair of Oxen exerts a force of 140 newton while ploughing the field. The field ploughed is 15 meter long. The work done in plou…

Question

A pair of Oxen exerts a force of 140 newton while ploughing the field. The field ploughed is 15 meter long. The work done in ploughing the length of the field is:

1. A. 1900 Joule
2. B. 2000 Joule
3. C. 2100 Joule (Correct answer)
4. D. 2200 Joule

Correct Answer

Option C — 2100 Joule

Detailed Solution & Explanation

The correct answer is 2100 Joule.

Key Points

• This is a direct application of the formula for work done by a constant force acting along the direction of displacement:
• Work (W) = Force (F) × Displacement (s) × cos θ
• Here the pair of oxen exerts a force of F = 140 newton, and the field ploughed is s = 15 metres long.
• Since the force acts along the direction of motion, θ = 0 and cos 0 = 1.
• Substituting: W = 140 × 15 = 2100 joules, which matches option (C).
• The joule is the SI unit of work and energy: 1 joule = 1 newton-metre, the work done when a force of one newton moves a body one metre in its own direction.

Exam Tip

• remember that work done is zero when the force is perpendicular to displacement (θ = 90°, cos 90° = 0) — which is why no work is done by the centripetal force in circular motion, or by a coolie carrying a load horizontally on his head, a classic conceptual question.

प्रश्न (हिन्दी में)

बैलों की एक जोड़ी खेत जोतते समय हल पर 140 न्यूटन का बल लगाती है। जोता गया खेत 15 मीटर लम्बा है। खेत की लम्बाई को जोतने में किया गया कार्य:

1. A. 1900 जूल
2. B. 2000 जूल
3. C. 2100 जूल
4. D. 2200 जूल