The displacement in simple harmonic motion is maximum when the

when the velocity is zero

the motion of a pendulum is a classic example of mechanical energy conservation. a pendulum consists of a mass (known as a bob ) attached by a string to a pivot point. as the pendulum moves it sweeps out a circular arc, moving back and forth in a periodic fashion.

beta is electron from nucleus

something from nucleus has changed, but charge must be same for cons of charge