Newton's Law of Gravitation

Definition

Newton's Law of Gravitation is a fundamental principle in physics that describes the attractive force between any two objects with mass. It establishes that the force of gravity between two objects is directly proportional to their masses and inversely proportional to the square of the distance between them.

5 Must Know Facts For Your Next Test

1. The gravitational force between two objects is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.
2. The gravitational constant, 'G', has a value of approximately 6.67 × 10^-11 N⋅m^2/kg^2, and is a universal constant that does not depend on the type of objects or their location.
3. The inverse square law of gravitation means that as the distance between two objects doubles, the gravitational force between them decreases by a factor of four.
4. Newton's Law of Gravitation explains the motion of planets and satellites, as well as the behavior of objects falling near the Earth's surface.
5. The gravitational force is always attractive, meaning that it pulls objects towards each other, and it acts instantaneously across any distance.

Review Questions

• Explain how Newton's Law of Gravitation relates to the motion of satellites in orbit around the Earth.
  • According to Newton's Law of Gravitation, the gravitational force between the Earth and a satellite in orbit is what keeps the satellite in its circular or elliptical path. The gravitational force is directed towards the center of the Earth and provides the centripetal force necessary to maintain the satellite's orbit. The strength of this gravitational force is determined by the masses of the Earth and the satellite, as well as the distance between them, as described by the inverse square law. This relationship between gravity and orbital motion is a key principle in understanding satellite orbits and the dynamics of celestial bodies.
• Describe how the inverse square law of gravitation affects the energy of a satellite in orbit.
  • The inverse square law of gravitation states that the gravitational force between two objects decreases with the square of the distance between them. This has a significant impact on the energy of a satellite in orbit. As a satellite moves farther away from the Earth, the gravitational force acting on it decreases, which in turn reduces the potential energy of the satellite. Conversely, as the satellite moves closer to the Earth, the gravitational force increases, and the potential energy of the satellite rises. This inverse relationship between distance and gravitational potential energy is a crucial factor in determining the total energy of a satellite, which is the sum of its kinetic and potential energies. Understanding this principle is essential for analyzing the energy changes and stability of satellite orbits.
• Evaluate how the gravitational force described by Newton's Law of Gravitation affects the motion and energy of objects in free fall near the Earth's surface.
  • According to Newton's Law of Gravitation, the gravitational force experienced by an object near the Earth's surface is directly proportional to the mass of the object and the mass of the Earth, and inversely proportional to the square of the distance between the object and the Earth's center. This gravitational force is what causes objects in free fall to accelerate towards the Earth's surface at a constant rate, known as the acceleration due to gravity (g). The strength of this gravitational force, as described by the inverse square law, determines the kinetic energy gained by the object as it falls, as well as the potential energy lost. Understanding the relationship between gravitational force, acceleration, and energy changes is crucial for analyzing the motion and behavior of objects in free fall, such as projectile motion and the dynamics of falling bodies near the Earth's surface.

Related terms

Gravitational Force: The attractive force that exists between any two objects with mass, as described by Newton's Law of Gravitation.

Gravitational Constant: A universal constant, denoted as 'G', that represents the strength of the gravitational force between two objects.

Inverse Square Law: The principle that the gravitational force between two objects decreases with the square of the distance between them.