A bracket is attached to a vertical column by means of two identical rivets U and V separated by a distance of 2a = 100 mm, as shown in the figure. The permissible shear stress of the rivet material is 50 MPa. If a load P = 10 kN is applied at an eccentricity e = 3√7 a, the minimum cross-sectional area of each of the rivets to avoid failure is ___________ mm².

Which of the following heat treatment processes is/are used for surface hardening of steels?

Which of the following additive manufacturing technique(s) can use a wire as a feedstock material?

Electrochemical machining operations are performed with tungsten as the tool, and copper and aluminum as two different workpiece materials. Properties of copper and aluminum are given in the table below.

$$ \begin{array}{|c|c|c|c|} \hline \text { Material } & \begin{array}{l} \text { Atomic mass } \\ \text { (amu) } \end{array} & \text { Valency } & \text { Density }\left(\mathrm{g} / \mathrm{cm}^3\right) \\ \hline \text { Copper } & 63 & 2 & 9 \\ \hline \text { Aluminum } & 27 & 3 & 2.7 \\ \hline \end{array} $$

Ignore overpotentials, and assume that current efficiency is 100% for both the
workpiece materials. Under identical conditions, if the material removal rate (MRR) of copper is 100 mg/s, the MRR of aluminum will be ________________ mg/s (round-off to two decimal places).