What is omegao the resonant frequency of the circuit just

Question

A circuit is constructed with a resistor, two inductors, one capacitor, one battery and a switch as shown. The value of the resistance is R₁ = 320 Ω. The values for the inductances are: L₁ = 240 mH and L₂ = 103 mH. The capacitance is C = 113 μF and the battery voltage is V = 12 V. The positive terminal of the battery is indicated with a + sign.

1) The switch has been closed for a long time when at time t = 0, the switch is opened. What is U_L1(0), the magnitude of the energy stored in inductor L₁ just after the switch is opened?

2) What is ω_o, the resonant frequency of the circuit just after the switch is opened?

3) What is Q_max, the magnitude of the maximum charge on the capacitor after the switch is opened?

4) What is Q(t₁), the charge on the capacitor at time t = t₁ = 3.55 ms. Q(t₁) is defined to be positive if V(a) - V(b) is positive.

5) What is t₂, the first time after the switch is opened that the energy stored in the capacitor is a maximum?

6) What is the total energy stored in the inductors plus the capacitor at time t = t₂?