phase angle question (SHM)

[sapiental]

question 1)

If a simple harmonic oscillation is described by the function

x = A sin (wt + phi)

would phi be the opposite of what it would be for a SHM described by the function

x = A cos (wt + phi)

I.e if the graph for for x = A sin (wt + phi) , when t = 0, x = +A. would phi be equal to pi instead of 0( as it would for x = A cos (wt + phi)


question 2)

For a mass m attached to a spring that undergoes simple harmonic motion, The spring
constant is k.

Does the elastic potential energy ever equal the kinetic energy at one point x?

this isnt a hw question, just my curiosity..

Thanks

[courtrigrad]

1. If x = A\sin(\omega t + \phi) and x = +A at t = 0 , then A = A\sin(\phi) .

So \phi = \frac{\pi}{2}

[sapiental]

thanks alot!