If the length is doubled, then the flexibility of a wire is increased by:

 # If the length is doubled, then the flexibility of a wire is increased by:

A. 4 times

B. 8 times

C. 2 times

D. 6 times

The correct answer is B. 8 times.

The stiffness of a wire is directly proportional to the fourth power of the radius and inversely proportional to the third power of its length. To put it more simply, flexibility is the direct opposite of stiffness therefore when the wire length is increased by 2 times the flexibility increases 8 fold, and if you increase the radius by 2 fold, the stiffness increase or flexibility decreases by 16 times.