The mass of a glider is 0.40 kg the spring constant = 1200 N/m. It is released form the right and feels a force of 24 N to the left?

The mass of a glider is 0.40 kg the spring constant = 1200 N/m. It is released from the right and feels a force of 24 N to the left? What is the frequency of the oscillation?
Answers

oldschool

ω = 2πf = √(k/m) f = (1/2π) *√(1200/0.4) = 8.7Hz