A 1.2kg mass attached to spring oscillates with an amplitude of 5.1cm and frequency 1.2Hz what is its energy of motion

Answer 1

omega = 2 pi f = sqrt (k/m)
2 pi * 1.2 = 7.54 = sqrt (k/1.2)
k/1.2 = 56.8
k = 68.1
at max amplitude speed = 0 so total energy = (1/2) k x^2
=(1/2) (68.1) (0.051)^2 = 0.0886 Joules