Engineering & Applied Science Fundamentals

Spherical roller bearings have a self-aligning feature because the barrel-shaped rollers can accommodate shaft misalignment. This design allows the bearing to adjust to angular deflection and shaft deflection without damage, making it ideal for applications where perfect alignment cannot be maintained.

Kaplan turbine is a low head axial flow turbine designed for applications with low water heads but high flow rates. Unlike Francis or Pelton turbines, Kaplan blades are adjustable to maintain efficiency across varying flow conditions. The option text appears truncated but the core concept is correct.

In spur gears, the base circle is the foundational circle from which the involute profile of the gear tooth is generated. It serves as the generating cylinder for the tooth curves.

Rain drops are spherical because of surface tension, which minimizes the surface area for a given volume. Surface tension acts equally in all directions, pulling the water into a shape with the smallest surface area - a sphere. Viscosity, air resistance, and atmospheric pressure affect falling behavior but not the spherical shape.

In a rigid flanged coupling, bolts are primarily loaded in shear due to the torque transmitted between shafts. The rigid connection also creates bending moments in the bolts because the flanges cannot rotate relative to each other, causing the bolts to resist both shear and bending. Axial force alone (B) is incorrect because the primary load is not along the bolt axis. Pure torsion (C) doesn't apply to bolts in this configuration. While torsion exists in the shafts, the bolts themselves experience shear and bending, not shaft torsion.

Acme threads are a specific type of trapezoidal thread with a 29-degree angle, commonly used for power transmission. Square threads have parallel sides rather than a trapezoidal profile, and 'Butters' is likely a misspelling of Buttress threads, which are triangular/asymmetric, not trapezoidal.

The M-system and E-system are both metrology standards used for measuring surface finish (roughness). M-system (Mottling system) and E-system (Envelope system) provide different ways to characterize surface texture - M-system uses mean line parameters while E-system uses envelope parameters. Gears (A) use specialized gear measuring systems. Screw threads (B) have thread measurement systems. Flatness (C) is a geometric tolerance measured differently.

Hydrostatic lubrication uses an external pump to pressurize and force lubricant between surfaces, creating a full fluid film even before motion starts. This means there's essentially no metal-to-metal contact at startup, giving the lowest starting friction among all lubrication types. Hydrodynamic (B) relies on relative motion to build pressure, so starting friction is higher. Mixed (C) and boundary (D) lubrication both involve some surface contact at start.

In rigid flanged couplings, bolts primarily experience shear force due to torque transmission between shafts and bending moment from any misalignment or external loads. The bolts don't directly carry torsional loads - that's what the shafts transmit.

Surface tension minimizes surface area, causing small water droplets to form spherical shapes. For falling rain drops, air resistance distorts this ideal shape, but surface tension is the fundamental reason for sphericity.

Hydrostatic lubrication maintains a complete fluid film even at zero speed by externally pressurizing the lubricant, giving very low starting friction. Hydrodynamic lubrication relies on relative motion to generate pressure film, so starting friction is higher.

Bernoulli's equation requires steady, incompressible, inviscid flow along a streamline. Turbulent flow is unsteady by definition and involves significant energy dissipation due to eddies, violating Bernoulli's assumptions. Rotational flows can also violate the irrotational requirement.

The Acme thread has a trapezoidal profile with sides inclined at 29°, designed for power transmission and easy manufacturing. Square threads have rectangular profiles, while buttress threads are asymmetric for unidirectional loads.

In metal cutting, material removal occurs through intense shear deformation along the shear plane. The cutting tool creates high stresses that cause the material to fail in shear, forming chips that curl away. This is a plastic deformation process, not linear translation.

Spherical roller bearings have a self-aligning feature due to their spherical raceway geometry, which accommodates misalignment between shaft and housing. Roller and needle roller bearings don't have this capability.

Kaplan turbine is a propeller-type reaction turbine with adjustable blades, designed for low-head applications. It's an axial flow turbine (water flows parallel to shaft), not mixed or outward flow. The 'low' in option B likely means 'low-head' despite the grammatical issue.

The M-system (mean line system) and E-system (envelope system) are two methods for assessing surface finish in metrology. M-system uses mean line as reference, while E-system uses envelope of surface peaks. They quantify roughness, waviness, and other surface texture parameters.

Bacillus anthracis is the correct causative agent of anthrax, a gram-positive bacterial infection. Junin virus causes Argentine hemorrhagic fever, not anthrax. Yersinia is a different bacterial genus, and Plasmodium causes malaria.