Question

Stretching DNA.
With its double-helix structure, DNA is coiled like a spring. A biophysicist grabs the ends of a DNA strand with optical tweezers and stretches it 26µm producing 1.2pN- tension in the strand.

What's the DNA's spring constant?

Answer 1

F=kx
F (tension of the strand)=1.2 pN
x (displacement)=26 µm

Solve for k, which is the spring constant. You may need to convert your unit measurements, as your answer's unit will come out in pN/µm instead of the standard N/m.

(I know this is a little late, but I wanted to post it up, in case anyone else needed it.)