Final answer:
Gravity is a force arising from the presence of mass, causing mutual attraction between masses. Newton's law of gravitation describes gravity as dependant on both the masses involved and their separation distance, which has implications for orbits, weight perception, and the motion of celestial entities.
Step-by-step explanation:
Gravity is a fundamental force that is present whenever there is mass in the universe, causing masses to attract each other. The force of gravitational attraction increases with the amount of mass and decreases with the distance between masses. On Earth, gravity gives us our sense of weight, and it governs the motion of celestial bodies, playing a critical role in orbits within our solar system and beyond.
Newton's law of gravitation formalized the understanding of gravity, stating 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. This principle is essential in calculating the gravitational effects between objects such as planets, stars, and galaxies.
Gravity's role in work and energy is also significant. It performs positive work when objects come closer together driven by gravitational pull, and the total work done by gravity over any closed path is zero, which classifies it as a conservative force. Because of gravity, you stay on the Earth instead of floating into space, but the force is never great enough to cause you to fall through its surface.