In welding, a current I is used to create a weld. Heat generated by radiation, or convection and conduction can be considered 0. The effect created by the current/arc in welding are in the direct internal heat generation mechanisms to be considered. Equations for the internal energy creation is shown:

Joule heating from current in wire:

q(gen, EE) = I^2 * Re (q(gen) in units of W and, I is in A, Re is ohms)

Joule heating from current @ electrical contact point:

q(gen, C) = I^2 * Rc

Joule heating from plasma @ end of wire:

q(gen, F) = I * V (V in volts)

The diameter of the wire is 1.5 mm, Re = 8E-3 ohm, Rc = 1E-3 ohm, and V = 5V. Temperature when wire enters control volume is 25 degrees celsius, and the molten drops leave at 2500 degrees celsius. The difference in enthalpy between both temps is 2E6 J/kg, steel density is 7000 kg/m^3.

1. Write an energy balance equation

2. Find an equation that companies U (m/s) as a function of current/other parameters

3. Find U when the current is 300 amps