Cavendish's torsion balance experiment (1798) measured
A{'text': 'The mass of the Sun in kilograms directly', 'label': 'A'}
B{'text': 'The straight-line distance from Earth to Moon', 'label': 'B'}
C{'text': 'The value of G, allowing calculation of Earth mass', 'label': 'C'}
D{'text': 'The speed of light in a vacuum in metres/second', 'label': 'D'}
Answer & Solution
Correct answer: C. {'text': 'The value of G, allowing calculation of Earth mass', 'label': 'C'}
1. Henry Cavendish used a torsion balance to measure the tiny gravitational force between lead balls.
2. From that force, he deduced the value of G ≈ 6.67 × 10⁻¹¹ N m² kg⁻².
3. Knowing G and g, one can compute Earth's mass M = g R² / G.
4. Cavendish is thus said to have "weighed the Earth".
_Source: NCERT Class 11 Physics, Ch 7 "Gravitation", §7.2_
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