Gravitational and Electric Fields

Charge

A property of protons and electrons.

The law of conservation of charge

The algebraic sum of the charges in an isolated system will remain constant.

Weight (Fg)

The gravitational force the earth exerts on any object on or near its surface.

Mass

The amount of matter in an object.

Newton's Law of Universal Gravitation

Every particle with mass in the universe attracts every other particle with a force which is directly proportional to the product of their masses and inversely proportional to the square of the distance between their midpoints.

Magnetic field

A magnetic field is a region of space where a magnet will experience a force.

Gravitational field

A gravitational field is a region of space where a mass will experience a force.

Gravitational field (strength or intensity)

The force acting per unit mass.

Electric field

An electric field is a region in space in which an electric charge experiences a force.

Coulomb's Law

Two point charges in free space or air exert forces in each other. The force is directly proportional to the product of the charges and inversely proportional to the square of the distance between the charges.

The magnitude of the electric field

The force per unit positive charge E = F/q where E and F are vectors.