代码如下
g = 9.8; l = 1.5; \[CapitalOmega] = Sqrt[g/l];
v0 = 0.2; w0 = v0/l;
s = NDSolve[{Derivative[2][\[Theta]][t] == -\[CapitalOmega]^2*
Sin[\[Theta][t]], \[Theta][0] == 0,
Derivative[1][\[Theta]][0] == w0}, \[Theta], {t, 0, 10}];
\[Theta] = \[Theta] /. s[[1]];
Plot[\[Theta][t], {t, 0, 10},
PlotStyle -> Thickness[0.004],
AxesStyle -> Thickness[0.003]]
Clear[g, l, \[CapitalOmega], v0, w0, s, \[Theta]]

得到的图形是这样的

我这里没有问题

没有问题+1