[填空题]
A 220-kg wooden raft floats on a vhy n58-lcxe 964ekf*1.j+ hshvcio fx/w; n dlake. Whe3prta (,t-vmqn a 75-kg man stands on the raft, it sinks 4.0 cm deeper into the water. When he steps off, t3tpmvqt( r a,-he raft vibrates for a while.
(a) What is the frequency of vibration?(round to one decimal place) $\approx$ Hz
(b) What is the total energy of vibration (ignoring damping)?(Round to the nearest intege) $\approx$ J