The mechanical response of a metallic bar to pulses of 30‐MeV protons has been investigated. It was found that by making the pulse duration short in comparison with the periods of the low‐order harmonics of the bar resonant oscillations, vibration amplitudes of the order of 10−11cm could be measured. The required energy loss by the beam pulses amounted to about 10−5J, and very simple theoretical considerations suffice to relate quantitatively the deposition of energy in the bar with the amplitudes of its natural vibrational modes.