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A string under tension produces a note of frequency 14Hz....

A string under tension produces a note of frequency 14Hz. Determine the frequency when the tension is quadrupled.

A.

14Hz

B.

18Hz

C.

28Hz

D.

56Hz

Correct answer is C

The formula for the frequency in a stringed instrument : f=12Tm

f = frequency; T = tension in the string; m = mass per unit lenth of the string.

f1 = 14 = 12Tm.

When T is quadrupled, we have

f2 = new frequency = 124Tm

= 2(12Tm)

= 2 f1

= 2 x 14 

= 28 Hz