Respuesta :

AL2006
Because PE is proportional to the height of where the mass is, and the top of the swing is the highest the mass of the 'bob' ever gets.
When pendulum is at the top of the swing, it is at the highest point of the swing. Since PE varies with height, it has the most PE at the top of the swing. Also, all the KE is converted to PE at the top, SO PE is highest at the top