# Physics vs Pure Math

• Jan 14th 2007, 02:31 PM
symmetry
Physics vs Pure Math
I know that in physics speed is called velocity or is it?

Is there a difference between speed and velocity?

In pure math: D = rt, where r = rate = speed.

In Physics: D = vt, where v = velocity = speed?????

Why?
• Jan 14th 2007, 02:42 PM
ThePerfectHacker
Quote:

Originally Posted by symmetry
I know that in physics speed is called velocity or is it?

Is there a difference between speed and velocity?

In pure math: D = rt, where r = rate = speed.

In Physics: D = vt, where v = velocity = speed?????

Why?

First, the meaning of "distance" and "speed" has absolutely nothing to do with pure math.

Speed is just a number. It can be expressed as a function that gives just numbers.

Velovity is a vector. It can be expressed as a function (called vector function) that gives both a number and the direction (the vector) in which some body is traveling.
• Jan 14th 2007, 06:11 PM
symmetry
ok
Eventually I will step into the world of vectors but for now, I am preparing for a very hard math test called CST-->Content Specialty Test covering grades 9-12 content.

Yes, the CST may be easy for a lot of people on this forum and others like it but not for everyone. I want to thank all the tutors on this site for helping me to see math in a new and shinning light.
• Jan 14th 2007, 10:16 PM
CaptainBlack
Quote:

Originally Posted by symmetry
I know that in physics speed is called velocity or is it?

Is there a difference between speed and velocity?

In pure math: D = rt, where r = rate = speed.

In Physics: D = vt, where v = velocity = speed?????

Why?

There are two related concepts velocity and speed, in 2 or more dimensions
velocity is a vector whose magnitude is how fast the body is going and
whose direction indicates which way it is going. The speed is a positive
scalar (ordinary number) indicating how fast the body is going.

In 1D motion the velocity is a directed number (that is either positive
or negative) the absolute value of which is how fast the body is going
and whose sign indicates if it is going to the right or left (or up or down).
The speed is again how fast the body is going and is always positive.

Also the speed in all cases is the magnitude of the velocity.

RonL