Answer:
Period of motion is approximately 0.5447 seconds
Step-by-step explanation:
We start by calculating the constant "k" of the spring which can be derived from the fact that an object of mass 12 g produced a stretch of 3.4 cm: (we write everything in SI units)
F = k * x
0.012 kg * 9.8 m/s^2 = k 0.034 m
k = 0.012 kg * 9.8 m/s^2 / (0.034 m)
k = 3.46 N/m
now we use the formula for the period (T) of a spring of constant k with a hanging mass 'm':

which in our case becomes:
