Harmonic excitation refers to a sinusoidal external force of a certain frequency applied to a system. ... Resonance occurs when the external excitation has the same frequency as the natural frequency of the system. It leads to large displacements and can cause a system to exceed its elastic range and fail structurally.
Open system because there is mass (water) flowing through the system of interest (radiator)
Answer:
That's either a cable-stayed bridge or a cantilever bridge
