• Cut-Off Diameter of Cyclone Separators:
• Lapple's Cut Diameter Equation ($d_{pc}$):

• Governing Factors:
• Inlet diameter / width ($W$): Determines the radial distance a particle must travel to strike the collector wall.
• Inlet air velocity ($v_i$): Generates the centrifugal vortex acceleration ($v_i^2 / r$).
• Effective number of turns ($N_e$): The number of helical gas revolutions inside the cyclone barrel and cone.
• (D) Pressure drop is a hydraulic consequence of gas flow rather than an independent parameter in the analytical cut-off equation.
• Conclusion: (A), (B) and (C) only (Option 2).

Correct option: (2) (A), (B) and (C) only,

• AutoCAD JOIN Command:
• Function: In Computer-Aided Design (AutoCAD), the JOIN command (J) connects collinear lines, open arcs, elliptical arcs, and splines that share common endpoints into a single continuous polyline object.
• Other Commands:
• Merge: Used in layers or data sets.
• Add: Mathematical insertion.
• Combine: Boolean 3D solid modeling command.
• Conclusion: Join (Option 4).

Correct option: (4) Join

• Velocity Ratio of Belt Drive Transmission:
• Formula:

• Calculation:
• Driving shaft speed ($N_1$) = $60\text{ rpm}$
• Driven shaft speed ($N_2$) = $170\text{ rpm}$

• Conclusion: Velocity ratio is 17/6 (Option 2).

Correct option: (2) 1716