Simple Harmonic Motion?

Question

I don't really understand the meaning of this equation.
x = B sin (wt + alpha), where B stands for amplitude.
What is alpha? And for omega, is it just linear speed?

Answer 1

For simple harmonic motion...
x (horizontal position of the pendulum or spring reference)
=
B (the amplitude of the wave)
*
sin( w (the angular velocity, in radians per second, of the oscillations)
*
t (time)
+
alpha (the reference time t0, also called angle offset) )
------------------------------
A simple pendulum, released at time t = 3 second, rocking back and forth 2 meteres left, and 2 meters right, 4 times every second, will have an equation as follows:
x = 2 * sin( 4 * 2pi * t - 3 * 2pi)

Answer 2

In that equation...

B is the amplitude of the oscillation.

w is the angular frequency, in radians per second. 2*pi radians per second corresponds to 1 cycle per second.

t is time, in seconds.

alpha is the phase, which is just the starting position of the oscillation at the start (when t=0). For example, if alpha = pi, the oscillation is 180 degrees (pi radians) out of phase with an oscillation that had the same frequency, but a phase of 0.