Newton's law of gravitation

Understanding Newton’s Law of Gravitation

  • Newton’s law of gravitation describes the gravitational attraction between two masses.
  • The law states that every pair of particles in the universe attracts each other with a force that is directly proportional to the product of their masses.
  • This force is also inversely proportional to the square of the distance between their centres.
  • The equation for Newton’s law of gravitation is F = G * (m1 * m2 / r^2) where F is the force of attraction between the masses, m1 and m2 are the masses of the particles, r is the distance between the centres of the two masses, and G is the gravitational constant.

Applying the Law of Gravitation

  • In order to apply the equation, always ensure to align your units, especially when calculating with expectations of standard SI units.
  • The gravitational constant, G, has a value of approximately 6.674 x 10^-11 N m^2/kg^2 in SI units.
  • Force is always a vector quantity, meaning that it has a direction as well as a magnitude. When objects are attracting each other due to gravity, the direction of the force is along the line between their centres.
  • It’s also key to note that the gravitational force is always attractive; there is no repulsion in Newton’s law of gravitation.

The Impact of Newton’s Law of Gravitation

  • Gravity, as described by Newton’s law of gravitation, acts on all objects and is responsible for keeping planets in orbit around the Sun.
  • The law also explains why objects have weight, which is due to the gravitational force pulling them towards the centre of the Earth.
  • Its many applications include calculations involving planetary motion, the tides, and the behaviour of satellites.
  • Understanding this law helps to tackle problems regarding gravity and its effects in the field of mechanics.

Examples utilising Newton’s Law of Gravitation

  • For instance, it can be used to calculate the force of gravity between the Earth (mass m1) and a 1kg mass (m2) at the Earth’s surface (distance r from Earth’s centre), using G, the gravitational constant.
  • Further, it can be used to calculate the force exerted by the sun on the planets, knowing the mass of the sun, the mass of a planet and their distance from each other.