Math Is Fun Forum

Whizzies

Member

Registered: 2014-07-18

Posts: 53

The function s(t) =vt what is the variable?

This function is only valid if the speed is constant. I have a question, I am trying to learn something very basic from the special relativity theorie. You can make an (s,t)-diagram from this function. My question is:

How do you know what is the variable in any given formula? The function s(t)=vt is a given function and the variable is t, but how could you find it out if the formula

was given?

And the diagrams what is the difference between a (s,t)-diagram and a (t,s)-diagram? I am taught to write down a (s,t)-diagram, but in the (hand-out; about relativity) they use an (t,s)-diagram.

how how? Ty

Bob

Administrator

Registered: 2010-06-20

Posts: 10,621

Re: The function s(t) =vt what is the variable?

hi Whizzies

If it has brackets t, s(t), this is a way of saying that the variables are t and s.  You can read it like this:

"s is a function of t; s is determined by multiplying t by v"

In general if s = vt, then all could be variables.

I would have a s,t diagram but it doesn't really matter.  A graph is still a graph, if you reverse the axes.

Some people insist that the across axis is the independent variable (ie. you choose the values for it) and the up axis is the dependent variable (ie. you work out its values from the formula or from the graph.  But even that isn't compulsory.

http://www.mathsisfun.com/sets/function.html

Bob

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

Whizzies

Member

Registered: 2014-07-18

Posts: 53

Re: The function s(t) =vt what is the variable?

hi Whizzies

If it has brackets t, s(t), this is a way of saying that the variables are t and s.  You can read it like this:

"s is a function of t; s is determined by multiplying t by v"

In general if s = vt, then all could be variables.

I would have a s,t diagram but it doesn't really matter.  A graph is still a graph, if you reverse the axes.

Some people insist that the across axis is the independent variable (ie. you choose the values for it) and the up axis is the dependent variable (ie. you work out its values from the formula or from the graph.  But even that isn't compulsory.

http://www.mathsisfun.com/sets/function.html

Bob

I've read that part, I am read a little bit about functions in functions and so on. Math seems to say a lot about formulas and graphs and how they behave, and it is the transition between the formula and graph that I find difficult sometimes. Cause for example if you have an (x,t)-diagram and you take the derivative from it you have speed and if you taak another derivative from the speed you get acceleration. But it is about points, its in that point and you can take differend points and make a graph from it.

you also have functions like:

f(z,y,x) = it is a threedimensional function, but a function with three variables is unsolvable (at least for me at this point) I still have some questions, but I have to think a little and practise a bit to formulate. Thanks for helping (: