Mark H. answered 11/19/19
Tutoring in Math and Science at all levels
If the spring is stretched 18cm and the spring constant is 65N/m, then the force is 0.018 * 65
The object will accelerate in accord with F = m*a
0.018 * 65 = 5.5 * a
a = 0.018 * 65 / 5.5 = 0.213m/sec^2
I don't know where you got the equations you used.....
One tip: include the units to make sure you have the numbers arranged correctly:
Force: F = 0.018 meters * 65 Newtons/meter = ____Newtons
F = ma:
Newtons = kg * meters/sec^2 (the definition of a Newton)