Excellent point! Thanks. At 10:16 AM 10/26/2013, Warren D Smith wrote:

if ropes were simply untwisted parallel strands, each a cylinder, and each strand assumed pre-cut at a random location, then pull on rope ==> it comes apart. Well, actually, the different strands will stick due to van der Waals forces, but it'll be very small tensile strength.

Contrast: with suitable twisted construction: apply tension, the outer strands compress the inner ones radially. This causes the strands to stick together due to friction =coeff*(normal force), and we now have positive normal force.

Now note, the normal force actually is *proportional* to applied tension which means no matter how much tension you apply, the rope will not break (assuming unbreakable strands) even though topologically speaking it already is broken by assumption.