57.]In certain ranges of a piano keyboard, more than one M string is tuned to the same note to provide extra loud- ness. For example, the note at 110 Hz has two strings at this frequency. If one string slips from its nor- mal tension of 600 N to 540 N, what beat frequency is heard when the hammer strikes the two strings simultaneously?

57.]In certain ranges of a piano keyboard, more than one M string is tuned to the same note to provide extra loud- ness. For example, the note at 110 Hz has two strings at this frequency. If one string slips from its nor- mal tension of 600 N to 540 N, what beat frequency is heard when the hammer strikes the two strings simultaneously?