Cavendish Experiment

Definition

The Cavendish experiment was a pioneering scientific investigation conducted in the late 18th century that provided the first experimental determination of the gravitational constant, a fundamental value in Newton's Law of Universal Gravitation. This landmark experiment demonstrated the existence of gravitational attraction between masses on a laboratory scale, laying the groundwork for our modern understanding of gravity.

5 Must Know Facts For Your Next Test

1. The Cavendish experiment was conducted by the English physicist Henry Cavendish in 1798, nearly a century after Newton published his theory of universal gravitation.
2. Cavendish used a torsion balance, a sensitive instrument that could measure the tiny gravitational attraction between two masses, to determine the value of the gravitational constant 'G'.
3. In the experiment, Cavendish suspended two small lead balls from the ends of a horizontal rod that was suspended by a thin wire. He then placed two larger lead balls near the smaller ones, and measured the tiny twisting of the wire caused by the gravitational attraction between the masses.
4. Cavendish's careful measurements and calculations allowed him to determine the value of the gravitational constant 'G' to be approximately 6.67 × 10^-11 N⋅m^2/kg^2, which is remarkably close to the modern accepted value.
5. The Cavendish experiment provided the first experimental evidence for Newton's Law of Universal Gravitation, demonstrating that the gravitational force acts between masses on a laboratory scale, not just between celestial bodies.

Review Questions

• Explain how the Cavendish experiment provided experimental support for Newton's Law of Universal Gravitation.
  • The Cavendish experiment was a groundbreaking investigation that directly measured the gravitational attraction between masses in a laboratory setting, rather than just observing the motions of celestial bodies. By using a sensitive torsion balance to detect the tiny gravitational pull between lead balls, Cavendish was able to determine the value of the gravitational constant 'G'. This experimental verification of the inverse square relationship between mass and distance, as described in Newton's Law of Universal Gravitation, was a major advancement in our understanding of gravity and its fundamental role in the universe.
• Describe the key components and setup of the Cavendish experiment, and explain how they enabled the measurement of the gravitational constant.
  • The Cavendish experiment utilized a torsion balance, which consisted of a horizontal rod suspended by a thin wire. At the ends of the rod were two small lead balls. Larger lead balls were then placed near the smaller ones, and the tiny twisting of the wire caused by the gravitational attraction between the masses was measured. By carefully recording the degree of twist and the distances between the balls, Cavendish was able to calculate the value of the gravitational constant 'G'. The torsion balance was a crucial component, as it allowed for the detection of the extremely small gravitational forces between the masses in the laboratory setting, which was a remarkable feat of experimental design and precision.
• Analyze the significance of the Cavendish experiment in the context of the development of our understanding of gravity and the laws of motion.
  • The Cavendish experiment represented a pivotal moment in the history of physics, as it provided the first experimental verification of Newton's Law of Universal Gravitation. By demonstrating that the gravitational force acts between masses on a laboratory scale, not just between celestial bodies, the experiment solidified the universal nature of gravity and its fundamental role in the physical world. The precise measurement of the gravitational constant 'G' was a crucial step in quantifying the strength of the gravitational force, which in turn enabled further advancements in our understanding of celestial mechanics, orbital dynamics, and the behavior of matter and energy in the universe. The Cavendish experiment, therefore, played a vital role in the development of classical mechanics and laid the groundwork for our modern theories of gravity and the laws of motion.

Related terms

Gravitational Constant: The gravitational constant, denoted as 'G', is a physical constant that represents the strength of the gravitational force between two objects. It is a crucial parameter in Newton's Law of Universal Gravitation.

Newton's Law of Universal Gravitation: Newton's Law of Universal Gravitation states that every particle in the universe attracts every other particle with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.

Torsion Balance: A torsion balance is a sensitive instrument used to measure small forces, such as the gravitational attraction between masses. It was a key component of the Cavendish experiment, allowing for the precise measurement of the gravitational constant.