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