In[]:=
m=10000;​​k=10000;​​w=16.67*6.28;​​F=10;​​S=NDSolve[{m*x''[t]+c*x'[t]+k*x[t]==F*Sin[w*t]},x''[0]==0,x'[0]==0,x[0]==0,x,{t,0,20}]
NDSolve
:
′
x
[0]0 cannot be used as a variable.
Out[]=
NDSolve[{10000x[t]+c
′
x
[t]+10000
′′
x
[t]10Sin[104.688t]},
′′
x
[0]0,
′
x
[0]0,x[0]0,x,{t,0,20}]