Answer:
This is a chemical property. If iron does rust, this is a slow chemical change since rust is an iron oxide with different properties than iron metal.
The period of any wave is the time it takes for its angle
to go from zero to 2pi .
The 'sin' function is a wave. The angle of this one is (8pi t).
When t=0, the angle is zero.
Wonderful.
Now, how long does it take for the angle to grow to 2pi ?
I*n other words, when is (8pi t) = 2pi ?
Divide each side by '2pi': . . . . . 4 t = 1
Divide each side by ' 4 ': . . . . . t = 1/4
And there you are. Every time 't' grows by 1/4, (8pi t) grows by 2pi.
So if you graph this simple harmonic motion described by 'd', you'll
see the graph wiggle up and down with a period of 1/4 .
