1.9 Obtain the TF of the following systems.
1.10 A Solenoid valve is shown in the figure below. The coil has the electric resistance of $4\Omega$ and an inductance of 0.6H and produce the electromagnetic force $F_c(t)=K_c\times i(t)$. The valve has the mass of 0.125kg and the liner bearings produce a resistive force of $C\times u(t)$. The value of $K_c$ and $C$ are 0.4N/A and 0.25Ns/m respectively. Deduce the over all differential equation relating the input voltage $v(t)$ to the output velocity $u(t)$.