A vertical mass-spring oscillator is displaced 2.0 cm from equilibrium. The 100 g mass passes through the equilibrium point with a speed of 0.75 m/s. What is the spring constant of the spring?
(A) 90 N/m
(B) 100 N/m
(C) 110 N/m
(D) 140 N/m
(E) 160 N/m

I was thinking of using kx = ma but then I realize that it is speed not a... :/ How do I do this problem?

Thank you.

Question

A vertical mass-spring oscillator is displaced 2.0 cm from equilibrium. The 100 g mass passes through the equilibrium point with a speed of 0.75 m/s. What is the spring constant of the spring?
(A) 90 N/m
(B) 100 N/m
(C) 110 N/m
(D) 140 N/m
(E) 160 N/m


I was thinking of using kx = ma but then I realize that it is speed not a... :/ How do I do this problem? 

Thank you.

anonymous · Answer

try conservation of energy.  

What is the potential energy of the stretched spring at the start. What is the kinetic energy  
of the mass as it passes through the equilibrium point.

be careful with your units.