The maximum speed of a 4.0-kg mass attached to a spring is 0.70 m/s , and the maximum force exerted on the mass is 12 N .
a) What is the amplitude of motion for this mass?
b) What is the force constant of the spring?
1/2 k x^2 = 1/2 m v^2
... k x^2 = 4.0 * 0.70^2 = 1.96
k x = 12
dividing equations ... x = 1.96 / 12
substitute back to find k