In an earthquake, it is noted that a footbridge oscillated up and down in a one loop (fundamental standing wave) pattern once every 2.

In an earthquake, it is noted that a footbridge oscillated up and down in a one loop (fundamental standing wave) pattern once every 2.8 s. What other possible resonant periods of motion are there for this bridge? What frequencies do they correspond to?1 s (n = 1)2 s (n = 2)3 s (n = 3)4 Hz (n = 1)5 Hz (n = 2)6 Hz (n = 3)