Henry Cavendish
Explanation
The Universal Law of Gravitation, formulated by Isaac Newton, posits that the gravitational force ($F$) between two masses is proportional to the product of their masses and inversely proportional to the square of the distance between them ($F = G \frac{m_1 m_2}{r^2}$). The proportionality constant, $G$, is known as the Universal Gravitation Constant.
Analysis of Options
- Isaac Newton: While Newton formulated the law of gravitation in his Principia Mathematica (1687), he did not calculate the numerical value of $G$. During his time, the experimental apparatus required to measure the extremely weak gravitational force between small terrestrial bodies did not exist.
- Henry Cavendish: In 1798, Henry Cavendish performed a famous experiment using a sensitive torsion balance to measure the force of attraction between lead spheres. This experiment, often referred to as "weighing the Earth," provided the data necessary to calculate the value of $G$ for the first time.
- Galileo Galilei: Galileo made foundational contributions to the study of kinematics and falling bodies but died before Newton formulated the law of gravitation.
- Blaise Pascal: Pascal is primarily associated with fluid mechanics (Pascal's Law) and probability theory, not gravitational physics.
Key Takeaway
Henry Cavendish experimentally determined the value of the Universal Gravitation Constant ($G$) using a torsion balance, more than a century after Isaac Newton formulated the Law of Gravitation.