Scalar and Vector Quantities

Figure One

Scalar Quantities

Most of the physical quantities encountered in physics are either scalar or vector quantities.

A scalar quantity is defined as a quantity that has magnitude only.

Typical examples of scalar quantities are time, speed, temperature, and volume.

A scalar quantity or parameter has no directional component, only magnitude.

For example, the units for time (minutes, days, hours, etc.) represent an amount of time only and tell nothing of direction.

Additional examples of scalar quantities are density, mass, and energy.

Vector Quantities (AHA! Vectoring comes from here!)

A vector quantity is defined as a quantity that has both magnitude and direction.

To work with vector quantities, one must know the method for representing these quantities.

Magnitude, or "size" of a vector, is also referred to as the vector's "displacement."

It can be thought of as the scalar portion of the vector and is represented by the length of the vector.

By definition, a vector has both magnitude and direction.

Direction indicates how the vector is oriented relative to some reference axis, as shown in Figure One.

Using north/south and east/west reference axes, vector "A" is oriented in the NE quadrant with a direction of 45 north of the o EW axis.

G iving direction to scalar "A" makes it a vector. The length of "A" is representative of its magnitude or displacement.

In short...

Scalar Quantities: Length, area, distance, work, temperature, time, volume, speed, energy, density

Vector Quantities: Displacement, Velocity, Force, Acceleration, Momentum

Magnitude is defined as... (Wiki)

The magnitude of a mathematical object is its size: a property by which it can be larger or smaller than other objects of the same kind; in technical terms, an ordering of the class of objects to which it belongs. (Huh?)

Direction is defined as... (Wiki)

Direction is the information contained in the relative position of one point with respect to another point without the distance information (Distance is Scalar).

Directions may be either relative to some indicated reference (the violins in a full orchestra are typically seated to the left of the conductor), or absolute according to some previously agreed upon frame of reference (New York City lies due west of Madrid).

I really, really don't understand this. But I shall keep on trying until I do. There are two teachers who are very convicted that girls CAN'T SUCCEED IN PHYSICS and I so wanna prove them WRONG.