Space / Time Relationships

Electric charge is the physical property of matter that causes it to experience a force when placed in an electromagnetic field. There are two types of electric charges: positive and negative (commonly carried by protons and electrons respectively). Like charges repel and unlike attract. An object with an absence of net charge is referred to as neutral. The SI derived unit of electric charge is the coulomb (C).

Energy is the property that must be transferred to an object in order to perform work on, or to heat, the object. The SI unit of energy is the joule, which is the energy transferred to an object by the work of moving it a distance of 1 metre against a force of 1 newton.

Thermal Resistance is a heat property and a measurement of a temperature difference by which an object or material resists a heat flow. Thermal resistance is the reciprocal of thermal conductance.

Angular Momentum is the rotational equivalent of linear momentum. It is an important quantity in physics because it is a conserved quantity – the total angular momentum of a system remains constant unless acted on by an external torque.

Jerk, also known as jolt, surge, or lurch, is the rate of change of acceleration; that is, the derivative of acceleration with respect to time, and as such the second derivative of velocity, or the third derivative of position.

Inertia is the resistance of any physical object to any change in its state of motion. This includes changes to the object's speed, direction, or state of rest.

Permittivity or absolute permittivity, usually denoted by the Greek letter ε (epsilon), is the measure of resistance that is encountered when forming an electric field in a particular medium. More specifically, permittivity describes the amount of charge needed to generate one unit of electric flux in a particular medium.

The SI unit for permittivity is farad per meter (F/m or F·m−1).
The lowest possible permittivity is that of a vacuum. Vacuum permittivity, sometimes called the electric constant, is represented by ε0 and has a value of approximately 8.85×10−12 F/m.

Conductivity, a measure of a material's ability to conduct an electric current.

Resistivity is a fundamental property that quantifies how strongly a given material opposes the flow of electric current. Reciprocal of conductance.

Momentum is the product of the mass and velocity of an object.

Impulse is the change of momentum of an object when the object is acted upon by a force for an interval of time. So, with impulse, you can calculate the change in momentum, or you can use impulse to calculate the average impact force of a collision.

Luminance is a photometric measure of the luminous intensity per unit area of light travelling in a given direction. It describes the amount of light that passes through, is emitted or reflected from a particular area, and falls within a given solid angle.

Compliance The inverse of stiffness is flexibility or compliance, typically measured in units of metres per newton. In rheology it may be defined as the ratio of strain to stress, and so take the units of reciprocal stress, e.g. 1/Pa.

Stiffness is the rigidity of an object — the extent to which it resists deformation in response to an applied force.

Capacitance is the ability of a body to store an electric charge.

Electric field is a field that surrounds electric charges. It represents charges attracting or repelling other electric charges by exerting force. The units of the electric field in the SI system are newtons per coulomb (N/C), or volts per meter (V/m).

Electrical resistance, of an electrical conductor is a measure of the difficulty to pass an electric current through that conductor.

Conductance, is the ease with which an electric current passes.

Inductance is a property of an electrical conductor which opposes a change in current. It does that by storing and releasing energy from a magnetic field surrounding the conductor when current flows, according to Faraday's law of induction. When current rises, energy (as magnetic flux) is stored in the field, reducing the current and causing a drop in potential (i.e., a voltage) across the conductor; when current falls, energy is released from the field supplying current and causing a rise in potential across the conductor.

Magnetic Reluctance, or magnetic resistance, is a concept used in the analysis of magnetic circuits. It is analogous to resistance in an electrical circuit, but rather than dissipating electric energy it stores magnetic energy. In likeness to the way an electric field causes an electric current to follow the path of least resistance, a magnetic field causes magnetic flux to follow the path of least magnetic reluctance.