SSC JE Mechanical flashcards
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32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Second differences rule
- In a number series, subtract consecutive terms to get first differences, then subtract again. A constant second difference means the series follows a quadratic pattern such as squares or n² + c.
- Clock hand angle formula
- The angle between hour and minute hands is the absolute value of 30H − 5.5M degrees, where H is the hour and M the minutes. Values above 180 are subtracted from 360.
- Syllogism validity test
- A conclusion follows only if it is true in every Venn diagram that satisfies all premises. Draw all possible overlap arrangements before accepting or rejecting a conclusion.
- Leap year day shift
- An ordinary year shifts the weekday of a given date by one day, while a leap year shifts it by two because of the extra 29 February. This underlies calendar repetition questions.
- Opposite letter pairs
- In the English alphabet, letters equidistant from the ends pair up so their positions sum to 27: A with Z, B with Y, M with N. Reverse position equals 27 minus forward position.
- Blood relation tree method
- Represent each person as a node, join generations vertically and siblings or spouses horizontally, and mark gender explicitly. Answer only after the full tree is drawn.
- Constitution adoption dates
- The Constitution of India was adopted by the Constituent Assembly on 26 November 1949 and came into force on 26 January 1950, the date celebrated as Republic Day.
- Fundamental Duties amendment
- Fundamental Duties were inserted by the 42nd Amendment Act of 1976 following the Swaran Singh Committee. They appear in Part IVA as Article 51A of the Constitution.
- Repo rate meaning
- The repo rate is the interest rate at which the Reserve Bank of India lends short-term funds to commercial banks against securities. Raising it generally tightens liquidity and curbs inflation.
- Tropic of Cancer states
- The Tropic of Cancer at about 23.5 degrees north passes through eight Indian states, including Gujarat, Rajasthan, Madhya Pradesh, Chhattisgarh, Jharkhand, West Bengal, Tripura and Mizoram.
- C. V. Raman Nobel
- Chandrasekhara Venkata Raman won the 1930 Nobel Prize in Physics for discovering the scattering effect named after him. He was the first Asian to receive a Nobel in science.
- SI base units
- The seven SI base units are metre, kilogram, second, ampere, kelvin, mole and candela, covering length, mass, time, electric current, temperature, substance amount and luminous intensity.
- RBI establishment year
- The Reserve Bank of India began operations in 1935 under the Reserve Bank of India Act, 1934, and was nationalised in 1949. It issues currency and manages monetary policy.
- Young's modulus definition
- Young's modulus is the ratio of tensile or compressive stress to the corresponding strain within the linear elastic limit. It has units of pascals and measures material stiffness.
- Simply supported beam central load
- For a simply supported beam of span L carrying a point load W at midspan, the maximum bending moment is WL/4 at the centre and reactions at each support are W/2.
- Cantilever end load deflection
- A cantilever of length L with a point load W at its free end has maximum bending moment WL at the fixed support and maximum deflection WL³/(3EI) at the free end.
- First law of thermodynamics
- For a closed system, heat supplied minus work done equals the change in internal energy. At constant pressure the heat supplied equals the change in enthalpy.
- Carnot efficiency
- The maximum possible efficiency of a heat engine operating between hot and cold reservoirs is 1 minus the ratio of cold to hot absolute temperatures, measured in kelvin.
- Ohm's law and power
- Voltage equals current times resistance. Electrical power equals voltage times current, and can also be written as current squared times resistance or voltage squared divided by resistance.
- Three-phase power formula
- Total power in a balanced three-phase circuit equals root three times line voltage times line current times power factor. In star connection line voltage is root three times phase voltage.
- Bernoulli's equation
- For steady, incompressible, frictionless flow along a streamline, pressure head plus velocity head plus elevation head stays constant. It underpins venturi and pitot tube analysis.
- Concrete nominal mixes
- Common nominal mixes are 1:1:2 for M25, 1:1.5:3 for M20, 1:2:4 for M15 and 1:3:6 for M10, given as cement to fine aggregate to coarse aggregate.
- Bending equation
- The bending equation states that bending moment divided by second moment of area equals bending stress divided by distance from neutral axis, which also equals Young's modulus divided by radius of curvature.
- Torsion of solid shaft
- For a solid circular shaft of diameter d under torque T, maximum shear stress equals 16T divided by pi d cubed, since the polar second moment of area is pi d⁴/32.
- Cantilever UDL deflection
- A cantilever of length L under uniformly distributed load w per unit length deflects a maximum of wL⁴/(8EI) at the free end, with maximum slope wL³/(6EI) there.
- Otto cycle efficiency
- Air-standard Otto cycle efficiency equals 1 minus one over compression ratio raised to the power gamma minus one. Higher compression ratio raises efficiency, limited by knock.
- Transformer EMF equation
- The induced EMF in a transformer winding equals 4.44 times frequency times turns times maximum flux. For an ideal transformer, voltage ratio equals turns ratio and inverse current ratio.
- DC motor back EMF
- Back EMF in a DC motor equals terminal voltage minus the product of armature current and armature resistance. It opposes the supply voltage and limits armature current.
- Induction motor slip
- Slip equals synchronous speed minus rotor speed, divided by synchronous speed. Synchronous speed itself equals 120 times supply frequency divided by number of poles.
- Simply supported beam UDL
- For a simply supported beam of span L under uniformly distributed load w per unit length, maximum bending moment is wL²/8 at midspan and maximum shear force is wL/2 at supports.
- Mechanical power from torque
- Shaft power equals two pi times rotational speed in revolutions per minute times torque in newton metres, divided by sixty, giving power in watts.
- Height of instrument method
- In leveling, height of instrument equals reduced level of a point plus its backsight reading. Intermediate and foresight readings are subtracted from it to obtain reduced levels.