Answer:
2.19 N/m
Explanation:
A damped harmonic oscillator is formed by a mass in the spring, and it does a harmonic simple movement. The period of it is the time that it does one cycle, and it can be calculated by:
T = 2π√(m/K)
Where T is the period, m is the mass (in kg), and K is the damping constant. So:
2.4 = 2π√(0.320/K)
√(0.320/K) = 2.4/2π
√(0.320/K) = 0.38197
(√(0.320/K))² = (0.38197)²
0.320/K = 0.1459
K = 2.19 N/m
