Why is packing tape nearly impossible to tear when intact, but easily shreds if you cut the slightest nick into it?

Question

Why is packing tape nearly impossible to tear when intact, but easily shreds if you cut the slightest nick into it?

In: 6079

Answer 1

Because in the second case, you’re tearing in the direction of the weakness in the material (the nick), while in the first case, there is no weakness in the material and so tearing it becomes very difficult.