Graphing a*b^0.3=constant: Which Variable Goes on the Y-Axis?

In summary, the conversation discusses how to sketch the graph of the equation a*b^0.3=constant for positive real numbers a and b. It is determined that using b as the horizontal axis and calculating values for b^0.3 and a based on a chosen constant will result in a curve with a negative slope and nonlinear shape. The conversation also mentions using online calculators like WolframAlpha or Mathematica to aid in graphing and determining values for equations. Additionally, the use of log axes is suggested as a way to linearize the graph and determine values for the exponent and constant.
  • #1
mech-eng
828
13
I would like to sketch the graph of equation a*b^0.3=constant for a and b are positive real numbers. How do I start?

Which one should be as y-axis, and which one be x-axis. This only affects the shape of the graph. The confusing part for me is that should I use b itself or b^03 as an axis?

Thank you.
 
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  • #2
I put b in the horizontal axis and give it values 10, 15, 20, 25, 30, 35, 40, 45 and calculated b^0.3 values. I choose constant=100 and then dividing 100/b^0.3 values I calculate a values. The graph is a curve with negative slope, nonlinear shape but it is like it behaves almost linear between b=20 and b=35 values.

Thank you.
 
  • #4
fresh_42 said:
Here's the graph ##ab^{0.3}=a \cdot (b^{0.3})=100## for control:
http://www.wolframalpha.com/input/?i=a*(b^0.3)=100
It's a hyperbola. The constants ##100## and ##0.3## are only a matter of scaling.
What is the name/category of this kind of web service? An online calculator?

Thank you
 
Last edited:
  • #5
mech-eng said:
What is the name/category of this kind of web service?

Thank you
I don't know, how it is named and by whom. Wolframalpha is a well-known company that provides solutions for simple equations. More detailed solutions and graphics have to be paid by a membership, but for a quick and dirty look-up, they are a good source. Here's another page with similar properties: https://www.desmos.com/calculator
 
  • #6
Are there CAD versions and multiphysics versions of such programs?

Thank you.
 
  • #7
mech-eng said:
Are there CAD versions and multiphysics versions of such programs?

Thank you.
I don't know. Perhaps you could search for them on Google. "free CAD software" of "physics simulations" could be a start.
 
  • #9
mech-eng said:
I would like to sketch the graph of equation a*b^0.3=constant for a and b are positive real numbers

In experimental work where you might be needing to determine the actual values for the exponent and the constant from your graph it is often useful to use log axes .

Simple example :

The function y = k . xn then it can be rewritten as log y = log k + n . log x

Plotted on log axes the graph curve now becomes a straight line with n and k being given by the slope and intercept .
 
  • #10
Is this a linearization process? This is very confusing for me because shape of the original and converted one is different so what is same?

Thank you.
 

1. What is the purpose of graphing an equation by hand?

Graphing an equation by hand allows us to visually represent the relationship between two variables and observe patterns or trends in the data. This can help us understand the behavior of the equation and make predictions about its values.

2. How do I choose the appropriate scale for my graph?

The scale of a graph is determined by the range of values for each axis. To choose an appropriate scale, consider the minimum and maximum values for each variable and divide the range into equal intervals. The more intervals, the more detailed the graph will be.

3. Can I use any type of graph to represent an equation?

While there are many types of graphs, such as bar graphs, pie charts, and scatter plots, the most common type for representing equations is a line graph. This is because equations typically involve two variables and a line graph can easily show the relationship between them.

4. How do I plot points on a graph?

To plot a point on a graph, locate the corresponding values for each variable on the axes and mark the point where they intersect. For example, if the equation is y = 2x + 1 and x = 3, then the point would be (3, 7).

5. What does it mean when a line on a graph is curved?

A curved line on a graph typically indicates a non-linear relationship between the variables. This means that the equation cannot be written in the form of y = mx + b (a straight line) and the relationship between the variables is more complex.

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