A Derivation on Pendulum swing that might be correct in Math but wrong in physics:

A Derivation on Pendulum swing that might be correct in Math but wrong in physics:

Derivation 1: 1/2 mv^2 = E ;; v= (2E/m)^(1/2) = x/ time;; Time= x/ (2E/m)^1/2;; Time = (x^2/(2(1/2kx^2))^1/2 x m^1/2 = (m/k)^1/2;; If v=r angle/ time x = r;; t= time = 2 pi (m/k)^1/2; Note:: angle= 2pi is a random hypothesis. Right in math but wrong in physics 1/2mv^2= 1/2 kx^2 = E does not apply in pendulum swing.

Derivation 2: Another way 1/2mv^2 = E = 1/2 kx^2 ;; mv^2= kx^2;; mx^2/t^2 = kx^2 ;; m/t^2= k;; t = time = (m/k) ^1/2;;; If v=r angle/ time x = r;; t= time = 2 pi (m/k)^1/2;; Note:: angle= 2pi is a random hypothesis. Right in math but wrong in physics 1/2mv^2= 1/2 kx^2 = E does not apply in pendulum swing.

Correct Formula: Pendulum swing time should be Time == Constant Variable (L(initial angle)/mass/g)