Physics Definitions and Concepts

Vocabulary study set covering vectors, kinematics, Newton's Laws, momentum, electric circuits, and the photoelectric effect based on lecture notes.

Vector quantity

A physical quantity that has both magnitude and direction.

Scalar quantity

A physical quantity that has magnitude only.

Resultant vector

A single vector which has the same effect as the original vectors acting together.

Distance

The length of path travelled. (Scalar)

Displacement

A change in position. (Vector)

Speed

The rate of change of distance. (Scalar)

Velocity

The rate of change of position or the rate of displacement or the rate of change of displacement. (Vector)

Acceleration

The rate of change of velocity. (Vector)

Weight ($F_g$)

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

Normal force ($F_N$)

The perpendicular force exerted by a surface on an object in contact with it.

Frictional force ($F_f$)

The force that opposes the motion of an object. (Know that it acts parallel to the surface with which the object is in contact.)

Newton's first law

An object continues in a state of rest or uniform (moving with constant) velocity unless it is acted upon by a net or resultant force.

Inertia

The property of an object that causes it to resist a change in its state of rest or uniform motion.

Newton's Second Law

When a net force, $F_{net}$, is applied to an object of mass, $m$, it accelerates in the direction of the net force. The acceleration, $a$, is directly proportional to the net force and inversely proportional to the mass.

Newton's Second Law (In terms of Momentum)

The net force acting on an object is equal to the rate of change of momentum.

Newton's Third Law

When object $A$ exerts a force on object $B$, object $B$ simultaneously exerts an oppositely directed force of equal magnitude on object $A$.

Linear momentum

The product of the mass and velocity of the object.

Impulse ($J$)

The product of the net force and the contact time.

Potential difference

The work done per unit positive charge.

Current

The rate of flow of charge.

Ohm's Law

Current through a conductor is directly proportional to the potential difference across the conductor at constant temperature.

Resistance

Material's opposition to the flow of electric charge.

EMF

The total energy supplied per coulomb of charge by the cell.

Threshold (cut-off) frequency ($f_o$)

The minimum frequency of incident radiation at which electrons will be emitted from a particular metal.

Work function ($W_0$)

The minimum amount of energy needed to emit an electron from the surface of a metal.