Which of the following is an ignition source that involves friction?

Which of the following is an ignition source that involves friction?

• A. Open flames
• B. Static electricity
• C. Friction
• D. Radiant heat

Answer: (C)

Friction creates heat when surfaces rub together, converting mechanical energy into thermal energy. In a setting with flammable vapors or combustible dust, that friction-generated heat can reach the ignition temperature of the mixture and ignite it. This makes friction an ignition source because the energy needed to start combustion comes from the rubbing action itself, not from an external flame or spark. Open flames provide direct flame energy, static electricity creates a discharge spark, and radiant heat comes from a hot object—friction is the heat produced specifically by motion between surfaces.

Friction creates heat when surfaces rub together, converting mechanical energy into thermal energy. In a setting with flammable vapors or combustible dust, that friction-generated heat can reach the ignition temperature of the mixture and ignite it. This makes friction an ignition source because the energy needed to start combustion comes from the rubbing action itself, not from an external flame or spark. Open flames provide direct flame energy, static electricity creates a discharge spark, and radiant heat comes from a hot object—friction is the heat produced specifically by motion between surfaces.