Answer:
Step-by-step explanation:
Your numbers seem wonky, so I'll just assume that the initial displacement is a distance A (Amplitude) from the equilibrium position. Spring constant = k
Initial potential energy is
PE = ½kA²
As potential energy and kinetic energy are constantly exchanging in SHM,
the position x where half of the original spring potential exists is found where
½kx² = ½(½kA²)
x² = ½A²
x = (√0.5)A
x ≈ 0.707A
just plug in your actual starting position A
With A = 5.2 cm
x = 3.67695... 3.7 cm