Which statement correctly describes elongation differences between static and dynamic kernmantle ropes?

• A. Static stretches no more than 20%; Dynamic stretches up to 60%
• B. Static stretches up to 60%; Dynamic stretches no more than 20%
• C. Both stretch up to 60%
• D. Neither stretches

Answer: (A)

Elongation under load is what makes static and dynamic kernmantle ropes behave so differently. Static rope is designed to stretch very little, so its elongation under load is limited—roughly 20% or less. Dynamic rope, on the other hand, is built to absorb energy by stretching a lot, so it can elongate substantially—often up to about 60% under dynamic loading. This contrast is why static lines are used when you need a predictable length for hauling or fixed-line work, while dynamic lines are used where energy absorption during a fall is important. Real-world factors like rope diameter, age, temperature, and loading rate can affect exact numbers, but the general pattern holds: low stretch for static, high stretch for dynamic.