Final answer:
In welding, the two methods of striking an arc are scratching and tapping, essential to start the electric arc for the welding process.
Step-by-step explanation:
The two methods of striking an arc in welding are scratching and tapping. These methods are used to initiate the electric arc required for the welding process. Scratching involves dragging the electrode across the metal, similar to striking a match, while tapping involves lightly touching the electrode to the metal and quickly pulling it away to create the arc.