An electrodeposition process of plating zinc onto steel for corrosion protection is expected to save energy over dipping steel into molten zinc (hot dipping), because it is necessary to keep the hot dip zinc molten continuously; whereas, with electrodeposition it is only necessary to run a current through the electrolyte during the electrodeposition process. The electrodeposition should take no more than 4 minutes to be competitive with hot dipping. With the electrodeposition equipment and agitation of the part and the solution it is found that a current density of 1 A/cm2 gives a coating of zinc that is satisfactory. What thickness and weight of zinc can be electroplated per square centimeter of steel in 4 minutes if the process is 100 % efficient?
What will be an ideal response?
Equation 10.15b applies to this problem. The current density is given, and all other terms in Equation 10.15b are then known except the weight of material.
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Determine the difference equations applicable to the centerline and at the surface of an axisymmetric cylindrical geometry with volumetric heat generation and convection boundary condition. Assume steady-state conditions.
GIVEN
Axisymmetric, steady, cylindrical geometry with volumetric heat generation and surface
convection boundary condition
FIND
(a) Difference equations for the centerline and surface
SKETCH
A segment of a drive shaft (d 5 200 mm, d 5 160 mm) is sub- 5 # 2 1 jected to a torque T 30 kN m. The allowable shear stress in the shaft is 45 MPa. The maximum permissible compressive load P is approxi-mately:
(A) 200 kN
(B) 286 kN
(C) 328 kN
(D) 442 kN
The figure below shows a planet traveling in a clockwise direction on an elliptical path around a star located at one focus of the ellipse. When the planet is at point A,
A. its speed is constant. B. its speed is increasing. C. its speed is decreasing. D. its speed is a maximum. E. its speed is a minimum.
A simple magnifier of refractive power 15.0 D is used to observe a beetle on a student’s desk. If the image of the beetle is formed at her nearpoint of 25 cm, how far is the beetle from the magnifier?
A. 50 cm B. 6.3 cm C. 4.2 cm D. 17 cm