In order to determine the acceleration of the block, use the following formula:
[tex]F=ma[/tex]Moreover, remind that for an object attached to a spring the magnitude of the force acting over a mass is given by:
[tex]F=kx[/tex]Then, you have:
[tex]ma=kx[/tex]by solving for a, you obtain:
[tex]a=\frac{kx}{m}[/tex]In this case, you have:
k: spring constant = 100N/m
m: mass of the block = 200g = 0.2kg
x: distance related to the equilibrium position = 14cm - 12cm = 2cm = 0.02m
Replace the previous values of the parameters into the expression for a:
[tex]a=\frac{(\frac{100N}{m})(0.02m)}{0.2\operatorname{kg}}=10\frac{m}{s^2}[/tex]Hence, the acceleration of the block is 10 m/s^2
