6. an arc welding machine delivers 4500 w of power to the surface of two steel plates that are to be joined by a butt weld. sixty percent (60%) of the power is transferred to an area that can be represented by a circle with a diameter of 5 mm. calculate the power density in w/mm2. answers are rounded to 2 decimal places (x. xx).
a. 137.51
b. 229.18
с. 687.55
d. 550.04
e. none of the above

Apiston-cylinder with a volume of 0.25 m3 holds 1 kg of air (r 0.287 k/kgk) at a temperature of 100 c. heat transfer to the cylinder causes an isothermal expansion of the piston until the volume triples. how much heat is added to the piston-cylinder?

Fluids at rest possess no flow energy. a)- true b)- false

Ahot wire operates at a temperature of 200°c while the air temperature is 20°c. the hot wire element is a tungsten wire of 5 um diameter and 2 mm in length. plot using excel current, heat transfer and heat generated by the wire for air velocity varying from 1-10 m/s in steps of lm/s? matlab the sensor voltage output, resistance, or assume nu 0.989 re033pr13 take air properties at tr (200°c20°c)/2 = 110°c properties of tungsten: c 0.13 kj/kg.k 3 p 19250 kg/m k (thermal conductivity) = 174 w/m.k