The relationship between the force $f(t)$ and the displacement $x(t)$ of a spring-mass system (with a mass $M$, viscous damping $D$ and spring constant $K$) is
$$M\frac{d^2x(t)}{dt^2}+D\frac{dx(t)}{dt}+Kx(t)=f(t).$$
$X(s)$ and $F(s)$ are the Laplace transforms of $x(t)$ and $f(t)$ respectively. With $\text{M=0.1, D=2, K=10}$ in appropriate units, the transfer function $G(s)=\frac{X(s)}{F(s)}$ is
- $\frac{10}{s^2+20s+100}$
- $s^2+20s+100$
- $\frac{10s^2}{s^2+20s+100}$
- $\frac{s}{s^2+20s+100}$