Sir Isaac Newton formulated the Universal Law of Gravitation, which explains how every object in the universe attracts every other object with a force. This force depends on the masses of the objects and the distance between them.
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Johannes Kepler (1571–1630) was a German astronomer and mathematician known for formulating the laws of planetary motion. In 1600, he became an assistant to the renowned astronomer Tycho Brahe in Prague. After Brahe's sudden death in 1601, Kepler was appointed Royal Mathematician.
Using Brahe's precise observations of planetary positions, Kepler discovered three fundamental laws of planetary motion, which describe how planets orbit the Sun. He wrote several influential books, and his work laid the foundation for Newton’s law of universal gravitation, which later explained the force governing planetary motion.
Johannes Kepler (1571–1630)
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"Every object in the universe attracts every other object with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them."
`F α (m_1m_2)/(d^2)`
`F = G(m_1m_2)/(d^2)`
where:
- F = Gravitational force between two objects
- m₁, m₂ = Masses of the two objects
- d = Distance between the centers of the objects
- G = Universal gravitational constant
The figure represents two objects with masses m₁ and m₂ separated by a distance d, attracting each other with equal and opposite gravitational forces (F).
Gravitational force between two objects
Newton’s law of gravitation explains:
- Planetary Motion: Why planets revolve around the Sun (explains Kepler’s laws).
- Earth-Moon System: Why the Moon stays in orbit around Earth instead of falling into it.
- Tides: The gravitational pull of the Moon and the Sun causes high and low tides on Earth.
- Orbital Motion: Artificial satellites stay in orbit due to Earth’s gravitational pull.
- Weight and Free Fall: Objects fall toward the ground because of Earth's gravity.
