Guide to Using
the graph applets.
To
interact with the graphs, points such a ‘a’ or ‘c’ can
be dragged to change variables in the equations.
When
zooming in, the point of interest can be centred by selecting an empty region
of the graph and holding the right mouse button and dragging.
The
details button shows the equations used for the plotted functions. The
equations can be edited.
Parametric
graphs are plotted by using the variable ‘t’ as the
parametric variable and entering an equation of the form (x(t),y(t)).
Normal
Cartesian graphs are plotted by using x as the main variable. To plot the graph
of y = x^2+5 then only x^2+5 would be entered in the function box.
A
point such as ‘a’ has two components. Ax is the
horizontal x component of a and ay is the vertical y
component of point a.
Point
a is usually used on this website to indicate the
apogee of the motion and only the horizontal ax
component is used in the equation. Point c is usually used to indicate an
intersection of light paths and both the cx and cy values are used in the equations.
The
applet software is fairly advanced and understands complex variables. Normally
when plotting an equation the real part of a complex value is plotted even if
there is a non zero imaginary part. To only plot purely
real values with no imaginary part the realonly() function should be used.
To plot the imaginary part of a complex value the im() function is used and
the re() function plots the real part of a complex value.
The
applet software is freely
available here and details of the numerous additional functions that can be
used can be found at the same link.
©
2008 KevPegrume.
dt = dT - 2m dr/(r-2m) in
equation 13.4