JSSC JE flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Great Bath

A large brick-lined water tank with steps found at Mohenjo-daro, interpreted as a ritual bathing pool of the Harappan civilisation, showing advanced drainage and water management.

Article 32

Constitutional guarantee of the right to move the Supreme Court for enforcement of Fundamental Rights, called the heart and soul of the Constitution by Dr. Ambedkar.

Repo rate

The interest rate at which the Reserve Bank of India lends short-term funds to commercial banks against government securities, used as a key monetary policy tool.

Tropic of Cancer in India

An imaginary latitude of about 23.5°N that passes through eight Indian states, including Rajasthan, Madhya Pradesh, Chhattisgarh, Jharkhand, West Bengal, Tripura, Mizoram and Gujarat.

Compound interest two years

For principal P and rate R percent per annum, compound interest for two years is P[(1 + R/100)² − 1], which exceeds simple interest by P(R/100)².

Successive percentage change

Two successive changes of a percent and b percent produce a net change of a + b + (ab/100) percent, with signs carrying signs of increase or decrease.

Work done together

If A alone finishes a job in x days and B in y days, working together they finish it in xy/(x + y) days, since their combined one-day rate is 1/x + 1/y.

Sphere volume

The volume enclosed by a sphere of radius r is (4/3)πr³, and its surface area is 4πr²; both formulas use the same radius.

Clock hand angle

The angle between hour and minute hands at H hours and M minutes is |30H − 5.5M| degrees, taking the smaller angle if the result exceeds 180 degrees.

Odd days in year

Remainder when total days are divided by seven: an ordinary year has one odd day, a leap year two, and a century has five odd days only if divisible by 400.

Grashof condition

A four-bar linkage satisfies Grashof if the shortest plus longest link is less than or equal to the other two links summed, allowing at least one full rotation.

Syllogism converse rule

From the statement 'All A are B' the valid inference is 'Some B are A'; the reverse 'All B are A' is not valid unless the two sets are identical.

Young's modulus

The ratio of tensile or compressive stress to the corresponding strain within the proportional limit, denoted E and measured in pascals or newtons per square millimetre.

Reynolds number

A dimensionless ratio of inertial to viscous forces, Re = ρVD/μ; pipe flow is generally laminar below about 2000 and turbulent above 4000.

Factor of safety

The ratio of the material's ultimate or yield stress to the permissible working stress, covering uncertainties in loading, material properties and fabrication quality.

Bernoulli equation

For steady, incompressible, frictionless flow along a streamline, pressure head plus velocity head plus elevation head stays constant, expressed as P/γ + v²/2g + z.

Cement initial setting time

Ordinary Portland cement must not set earlier than 30 minutes after adding water, allowing time for mixing, transport and placing of concrete.

Height of instrument

In levelling, the reduced level of a benchmark plus the backsight reading on it; subtracting a foresight from it gives the reduced level of the next point.

Active earth pressure coefficient

For cohesionless backfill with angle of internal friction φ, Ka equals (1 − sinφ)/(1 + sinφ), used to compute lateral thrust on a retaining wall.

Stopping sight distance

The distance a driver needs to stop after spotting an obstacle, equal to lag distance plus braking distance, calculated as 0.278Vt + V²/(254f).

BOD5

Biochemical oxygen demand measured over five days at 20 degrees Celsius, indicating biodegradable organic matter in water; domestic sewage typically shows 200 to 300 mg/L.

Carnot efficiency

The maximum possible efficiency of a heat engine operating between hot and cold reservoirs, equal to 1 minus the ratio of their absolute temperatures.

Diesel cycle efficiency

Efficiency of the constant-pressure heat addition cycle, depending on compression ratio, cut-off ratio and specific heat ratio; lower than Otto efficiency for the same compression ratio.

Torsion formula

For a circular shaft, shear stress varies linearly with radius: τ/r = T/J = Gθ/L, giving maximum shear stress 16T/(πd³) for a solid shaft.

Taylor's tool life equation

Empirical relation VTⁿ = C linking cutting speed V and tool life T, where n and C depend on tool and workpiece materials; higher n means slower tool wear.

Economic order quantity

The order size minimising total inventory cost, given by the square root of 2DS/H, where D is annual demand, S ordering cost and H holding cost per unit.

Critical path

The longest-duration path through a project network; activities on it have zero total float and any delay there delays project completion.

Section modulus

The ratio of the second moment of area to the distance to the extreme fibre, Z = I/ymax, so maximum bending stress equals M/Z.

M20 concrete mix

A nominal concrete mix of 1:1.5:3 by volume of cement, fine aggregate and coarse aggregate, giving characteristic cube strength of 20 N/mm² at 28 days.

Chezy's formula

Open channel velocity V = C√(RS), where C is the Chezy coefficient, R the hydraulic radius and S the bed slope, applicable to uniform flow.

Superelevation

The inward transverse slope provided on horizontal road curves to counter centrifugal force, computed as e = V²/(127R) minus the design friction factor.

Cut-off ratio

In the Diesel cycle, the ratio of cylinder volume after constant-pressure heat addition to volume before it; a larger cut-off ratio lowers cycle efficiency.