Gravity | Definition, Physics, & Facts | Britannica
2024年9月25日 · Gravity is measured by the acceleration that it gives to freely falling objects. At Earth ’s surface the acceleration of gravity is about 9.8 meters (32 feet) per second per second. Thus, for every second an object is in free fall, its speed increases by …
Newton’s law of gravitation | Definition, Formula, & Facts | Britannica
5 天之前 · planetary orbits: Kepler, Newton, and gravity Brian Greene demonstrates how Newton's law of gravitation determines the trajectories of the planets and explains the patterns in their motion found by Kepler.
Newton’s law of gravity - Encyclopedia Britannica
2024年9月25日 · Newton was thus able to show that all three of Kepler’s observationally derived laws follow mathematically from the assumption of his own laws of motion and gravity. In all observations of the motion of a celestial body, only the product of G and the mass can be found.
Gravity - Force, Physics, Theory | Britannica
2024年9月25日 · The Newtonian theory of gravity is based on an assumed force acting between all pairs of bodies—i.e., an action at a distance. When a mass moves, the force acting on other masses had been considered to adjust instantaneously to the new location of the displaced mass.
Development of gravitational theory | Britannica
gravity, Universal force of attraction that acts between all bodies that have mass. Though it is the weakest of the four known forces, it shapes the structure and evolution of stars, galaxies, and the entire universe.
Center of gravity | Definition & Facts | Britannica
Center of gravity, in physics, an imaginary point in a body of matter where, for convenience in certain calculations, the total weight of the body may be thought to be concentrated. In a uniform gravitational field, the center of gravity is identical to the center of mass.
Friction | Definition, Types, & Formula | Britannica
2024年9月11日 · All About Physics Quiz Static friction , in contrast, acts between surfaces at rest with respect to each other. The value of static friction varies between zero and the smallest force needed to start motion.
Gravity - Acceleration, Earth, Moon | Britannica
2024年9月25日 · Two basic ways of making absolute measurements of gravity have been devised: timing the free fall of an object and timing the motion under gravity of a body constrained in some way, almost always as a pendulum.
Weight | Gravity, Mass & Force | Britannica
2024年10月17日 · Alternatively, weight is the product of an object’s mass and either the gravitational field or the acceleration of gravity at the point where the object is located. Units of weight are those of force, not mass ( see force ).
Gravity - Fields, Relativity, Theory | Britannica
2024年9月25日 · Predictions by classical physics and general relativity that light passing close to the Sun might be deflected are described above. There are two further consequences for astronomy . Light from a distant object may pass close to objects other than the Sun and be deflected by them.