A 075-M-Long Piano Wire (Radius of 0 $2 \times 10 ^ { 11 }$

Multiple Choice

A 0.75-m-long piano wire (radius of 0.5 mm) has one end fixed and the other end attached to a rotatable tuning peg (having a radius of 2 mm) . The tuning peg is rotated so that the wire is just taut, and then the peg is given three full turns (tightening the wire) . If the Young's modulus is $2 \times 10 ^ { 11 }$ Pa, the tension in the piano wire is

A) 7900 N.
B) 6600 N.
C) 5600 N.
D) 4400 N.