Tutor profile: Amanda A.

What is the difference between a local and global variable?

Global variables are defined in the main body of a script or defined as 'global' within a function such that they can be called and used anywhere in the program. Local variables are defined within a function and are unknown to the rest of the program outside of that function.

In integration and/or differentiation, what is 'dx'?

dx is an infinitesimally small chunk of the variable x. By looking at a graph of a function, imagine cutting smaller and smaller slices vertically along the x-axis. These slices can then be multiplied by the integrand and summed up in an infinite sense (for an integral), or used to determine slope for a derivative.

How does the moon cause tides on Earth?

The moon, like the Earth, has gravity that creates a tidal force on the Earth. The tidal force can be visualized as the Earth stretching the Earth along the Earth-Moon line creating a bulge nearest the moon and farthest from the moon (the bulge nearest the moon is larger). The Earth rotates about it's own axis once per day, resulting in a given point passing through these two bulges -- and thus two high and two low tide -- each day.