Accepted Answer
Frequency = vibrations per second[ (480 vibrations) / (4minutes) ] x [ 1 minute / 60 seconds ] = 2 vibrations / secPeriod = 1 / frequency = 1/2 second
Frequency = vibrations per second[ (480 vibrations) / (4minutes) ] x [ 1 minute / 60 seconds ] = 2 vibrations / secPeriod = 1 / frequency = 1/2 second