Question

Please help! Applying force =(30 sin(wt)) driving a spring at undampened resonant freq at w=10, how to find resonant steady state amplitude

k=100N/m
m=1kg
w=sqrt(k/m)=10
Fapp=30 sin(10t)
Fnet=-kx+Fapp
m*x''(t)=-kx(t)+30sin(10t)
x''(t)=-100 x(t)+30sin(10t)
I solved this ode with numerical methods, and the solution is diverging, my notes say the Amplitude at resonance should only be 0.215 m

Answer 1

@zepdrix

Answer 2

would it be
mx''(t) = -kx+Fapp?