What Is the Gravitational Constant?

Gravitational constant is a physics term. The currently recognized result is a Cavendish G value of 6.754 × 10 ^-11 N · m² / kg². The latest recommended standard is G = 6.67259 × 10 ^-11 N · m². / kg², usually G = 6.67 × 10 ^-11 N · m² / kg², if using the centimeter-gram system, G = 6.67 × 10 ^ -8 dyn · cm² / g².

Gravitational constant

Gravitational constant, yes

The gravitational constant is G = 6.672x10 ^ -11

Newton found

Gravitational constant determination

It should be emphasized that when Newton came to the planet's gravitational relationship to the sun, it had infiltrated the hypothetical factors. After Henry Cavendish measured the gravitational force between some objects and calculated the gravitational constant G, he also measured the gravitational force between various objects. The results obtained were the same as those obtained by using the gravitational constant G according to the law of universal gravitation. Therefore, the universality of the gravitational constant becomes the correct witness of the law of universal gravitation.

This is a model of Cavendish twist scale. The main part of this twist scale is such a T-shaped light and strong frame, which is hung upside down under a quartz wire. If two forces of equal size and opposite directions are applied to the two ends of the T-shaped frame, the quartz wire will twist at an angle. The greater the force, the greater the angle of twist. Conversely, if the angle of rotation of the T-shaped frame is measured, the magnitude of the force on the two ends of the T-shaped frame can also be measured. A small ball is fixed at each end of the T-shaped frame, and then a large ball is placed near each small ball. The distance between the two balls can be easily determined.

According to the law of universal gravitation, a large ball will attract the small ball, and the T-shaped frame will twist with it. As long as the angle of twist is measured, the magnitude of gravity can be measured. Of course, due to the small gravity, the angle of this twist will be small. How can we measure this angle? Cavendish installed a small mirror on the T-shaped frame, using a beam of light to the mirror, and the light reflected by the mirror was directed to a distant scale. When the mirror and the T-shaped frame made a small rotation together, The light spot on the scale will move greatly. In this way, it has an effect of reducing the size of the large ball. By measuring the movement of the light spot, the angle of twist of the T-shaped frame before and after the large ball is placed is measured, so that the gravity of the small ball to the small ball is measured at this time.

Cavendish used this torsion scale to verify Newton's law of gravity and determine the value of the gravitational constant G. This value is very close to the value measured by a more scientific method in modern times. ^[1]