Which one of the following is not a product that has been made with Kevlar?

Correct Option: Bungee jumping cords

Explanation:

Kevlar is a synthetic polymer (an aramid fiber) known for its high tensile strength-to-weight ratio, high heat resistance, and exceptional toughness. It is around five times stronger than steel on an equal weight basis.

Let us examine the common applications of Kevlar:

1. Body armor: Kevlar is widely famous for its use in bulletproof vests and helmets due to its high impact resistance and energy absorption capabilities.
2. Brake pads: High thermal stability and resistance to friction make Kevlar an excellent material for automotive brake pads.
3. Tennis racquets: Kevlar fibers are blended into composite materials for sports equipment like tennis racquets to add rigidity and reduce vibration without adding significant weight.

Why Bungee Jumping Cords are NOT made with Kevlar:
Bungee jumping cords require extreme elasticity and high stretchability to absorb kinetic energy safely during a drop. Kevlar, on the other hand, is extremely rigid and has very low elasticity (it does not stretch significantly under tension). Using Kevlar for bungee cords would result in a rigid, non-stretching rope, which could lead to severe injury. Therefore, bungee cords are primarily made of natural or synthetic rubber threads encased in a woven fabric sheath (usually nylon or polypropylene).

Hence, Bungee jumping cords is NOT a product made with Kevlar.