MPPSC SES Mechanical flashcards
MPPSC SES Mechanical · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Euler buckling load
- The critical axial load at which an ideal slender column becomes unstable: P_cr = π²EI/L_e², where L_e is the effective length set by end conditions.
- Parallel axis theorem
- The second moment of area about any axis equals that about a parallel centroidal axis plus the area times the square of the distance between the axes: I = I_G + A·d².
- Torsion equation
- For a circular shaft in pure torsion, shear stress divided by radius equals torque divided by polar moment, and also equals shear modulus times twist per unit length.
- Soderberg criterion
- A fatigue design line relating alternating stress to mean stress using yield strength as the mean-stress limit, more conservative than the Goodman straight line for ductile materials.
- Goodman relation
- Fatigue failure criterion in which the ratio of alternating stress to endurance limit plus the ratio of mean stress to ultimate tensile strength equals one.
- Wahl factor
- A stress correction factor for helical springs that accounts for direct shear and curvature effects, raising the calculated shear stress above the simple torsion value.
- Grashof condition
- A four-bar linkage has at least one fully rotating link when the sum of the shortest and longest link lengths does not exceed the sum of the other two.
- Logarithmic decrement
- The natural logarithm of the ratio of two successive peak amplitudes in damped free vibration, equal to 2πζ divided by the square root of one minus ζ squared.
- Isochronous governor
- A governor whose equilibrium speed remains constant over its entire range of sleeve lift, giving zero sensitivity; the controlling force curve passes through the origin.
- Critical speed of shaft
- The rotational speed at which a shaft's rotation frequency matches its natural lateral frequency, producing resonant whirling and potentially destructive amplitudes.
- Hydraulic diameter
- Four times the flow cross-sectional area divided by the wetted perimeter, used to extend pipe-flow Reynolds number and friction correlations to non-circular ducts.
- Specific speed of turbine
- A dimensionless-type index, N√P divided by H raised to the power 5/4, used to classify turbines as Pelton, Francis or Kaplan for a given head and power.
- Net positive suction head
- The absolute pressure head at the pump suction above vapour pressure; available NPSH must exceed required NPSH to prevent cavitation and loss of performance.
- Carnot efficiency
- The maximum possible efficiency of a heat engine between two reservoirs, equal to one minus the ratio of sink temperature to source temperature, both absolute.
- Log mean temperature difference
- The effective driving temperature difference for a heat exchanger, computed as the difference of terminal differences divided by the natural log of their ratio.
- Biot number
- The ratio of internal conduction resistance to external convection resistance; values below about 0.1 allow lumped capacitance analysis of transient cooling or heating.
- Taylor tool life equation
- An empirical relation VT^n = C linking cutting speed to tool life, where the exponent n depends mainly on tool material and C on the tool-work combination.
- Merchant shear angle
- The relation predicting the shear plane angle in orthogonal cutting from rake angle and friction angle, derived by minimising cutting force.
- Chvorinov rule
- Solidification time of a casting is proportional to the square of the ratio of volume to surface area, used to size risers that freeze after the casting.
- Economic order quantity
- The order size minimising total ordering and holding cost, equal to the square root of twice annual demand times ordering cost divided by holding cost per unit.
- PERT expected time
- A weighted activity duration estimate, one sixth of optimistic plus four times most likely plus pessimistic, used in probabilistic network scheduling.
- Learning curve
- A model in which unit time falls by a constant percentage each time cumulative output doubles, expressed as the exponent of cumulative quantity.
- Hall-Petch relation
- Yield strength increases with the inverse square root of grain diameter, explaining why fine-grained metals are stronger and usually tougher.
- Martensite
- A hard, brittle phase formed by diffusionless shear transformation of austenite during rapid quenching; its hardness increases with the carbon content of the steel.
- Eutectoid reaction
- On cooling, a single solid phase transforms into two solid phases simultaneously; in steel, austenite becomes pearlite at about 0.76 percent carbon.
- Passive chromium oxide film
- A thin, self-healing surface layer that protects stainless steel from corrosion, forming when chromium content is roughly 10.5 percent or higher.
- Cayley-Hamilton theorem
- Every square matrix satisfies its own characteristic equation, allowing powers of the matrix to be reduced and the inverse to be found.
- Reynolds number
- A dimensionless ratio of inertial to viscous forces, used to classify flow regime and select friction correlations in pipes and over bodies.
- Fundamental Duties
- Eleven duties of citizens listed in Part IVA of the Indian Constitution, inserted by the 42nd Amendment in 1976 on a committee recommendation.
- Narmada river
- A major west-flowing river of Madhya Pradesh rising at Amarkantak, flowing through a rift valley between the Vindhya and Satpura ranges.
- Average speed, equal distances
- When two equal distances are covered at speeds u and v, the average speed over the whole journey is twice their product divided by their sum.
- Whistleblowing justification
- Disclosure of wrongdoing is ethically defensible when serious public harm is likely, evidence is documented, internal channels have failed, and disclosure is proportionate.