The true value of G, the universal gravitational constant, is approximately 6.674 × 10⁻¹¹ m³ kg⁻¹ s⁻² (or N⋅m²/kg²).
Understanding the Universal Gravitational Constant (G)
G, often referred to as the universal gravitational constant, is a fundamental constant in physics that determines the strength of the gravitational force between two objects with mass. It's a crucial component in Newton's Law of Universal Gravitation:
F = G (m₁ m₂) / r²
Where:
- F is the gravitational force between the two masses.
- m₁ and m₂ are the masses of the two objects.
- r is the distance between the centers of the two objects.
The Value of G
While the acceleration due to gravity (g) varies depending on location (e.g., on Earth, it's approximately 9.81 m/s²), G is a universal constant, meaning its value remains the same throughout the universe. The currently accepted value, as of 2018 according to the Committee on Data for Science and Technology (CODATA), is:
G = 6.67430 × 10⁻¹¹ m³ kg⁻¹ s⁻²
This value is extremely small, which is why gravity is a relatively weak force compared to other fundamental forces like electromagnetism or the strong nuclear force. It is also very hard to measure precisely.
Importance of G
The universal gravitational constant plays a crucial role in numerous areas of physics and astronomy, including:
- Calculating gravitational forces: Used to determine the gravitational force between celestial bodies like planets, stars, and galaxies.
- Predicting orbital motion: Essential for predicting the paths of satellites, planets, and other objects in orbit.
- Modeling the universe: Plays a vital role in cosmological models that describe the structure and evolution of the universe.
Measuring G
Determining the exact value of G is a challenging task. The most common method involves using a torsion balance, an instrument that measures the tiny twisting force between two masses. Early experiments were famously performed by Henry Cavendish in the late 18th century. Modern experiments continue to refine the accuracy of G's value.
