a welding torch produces a flame by burning acetylene fuel in the presence of oxygen. this flame is used to melt a metal. which energy transformation represents this process?
chemical energy into thermal energy
potential energy into kinetic energy
kinetic energy into electromagnetic energy
potential energy into chemical energy

The answer is;  chemical energy into thermal energy

The chemical energy is held in the chemical bonds of the molecules of the acetylene fuel. When the fuel is burned in the presence of oxygen, the amount of energy produced is high (through an exothermic process) and produces a flame. The flame is hot enough to melt metal. Melting occurs when the thermal energy excites molecules and they begin to move fast and overcome the metallic bonding of the metal lattice.

A

Explanation:chemical energy to thermal energy

- measure reactants precisely. ( first choice)

- stir to the reaction take place. ( second choice)

- wait patiently until the reaction completes. ( fourth choice)

- make sure to recover as much copper as possible. ( last choice)

the motion of a pendulum is a classic example of mechanical energy conservation. a pendulum consists of a mass (known as a bob ) attached by a string to a pivot point. as the pendulum moves it sweeps out a circular arc, moving back and forth in a periodic fashion.