CSAT Vocational Inquiry cheat sheet

Crop rotation with legumes fixes atmospheric nitrogen via Rhizobium symbiosis, cutting synthetic N fertilizer need; alternating deep- and shallow-rooted crops reduces soil compaction and pest buildup.

Photosynthesis net equation: 6CO2 + 6H2O + light energy → C6H12O6 + 6O2; light-dependent reactions occur in thylakoid membranes, the Calvin cycle in the stroma.

Soil pH governs nutrient availability: most field crops favor pH 6.0–7.0; below 5.5 aluminum toxicity and phosphorus lock-up increase, corrected by liming (CaCO3 or Ca(OH)2).

N-P-K labels give percent elemental N, P2O5, and K2O by mass; 100 kg of 20-10-10 supplies 20 kg N, 10 kg P2O5, and 10 kg K2O.

Integrated pest management decision rule: act only when pest counts exceed the economic threshold; rotate modes of action to slow resistance, and prefer biological/cultural controls first.

Grafting joins a scion (fruit-bearing top) to a rootstock (root system); rootstock choice controls vigor, soil-borne disease resistance, and cold tolerance.

Animal breeding: heritability (h²) estimates the share of phenotypic variance that is genetic; selection response R = h² × selection differential S.

Greenhouse transplanting rule: harden seedlings by gradually lowering temperature and water 7–10 days before field setting to reduce transplant shock.

Ohm's law: V = I × R; power P = V × I = I²R = V²/R. In a series circuit current is equal everywhere; in parallel circuits voltage is equal across branches.

Three-phase power: P = √3 × V_L × I_L × power factor for a balanced load; power factor = kW/kVA.

A transformer changes AC voltage by turns ratio V1/V2 = N1/N2; it cannot change frequency and works only on AC.

Gear ratio = driven teeth ÷ driver teeth; a ratio > 1 reduces speed and increases torque proportionally (ignoring losses).

Cutting speed for turning: v = π × D × n / 1000 (v in m/min, D in mm, n in rpm); higher hardness demands lower speed and greater coolant flow.

Bearing clearance and lubrication rule: hydrodynamic lubrication requires a continuous oil film; insufficient film causes metal-to-metal contact and seizure.

PLC scan cycle order: read inputs → execute program → update outputs, repeated cyclically; scan time limits how fast an input change can be detected.

Bearing/steel heat treatment: quenching forms martensite (hard, brittle), then tempering relieves internal stress and restores toughness.

Accounting equation: Assets = Liabilities + Equity; every transaction keeps it balanced (double entry).

Profit = Revenue − Expenses; gross profit = Sales − Cost of goods sold; operating profit also deducts operating expenses.

Break-even quantity = Fixed costs ÷ (Unit price − Unit variable cost); the denominator is the contribution margin per unit.

Current ratio = Current assets ÷ Current liabilities; a value near 1.5–2.0 generally signals adequate short-term solvency.

Depreciation straight-line = (Cost − Residual value) ÷ Useful life; declining balance applies a fixed rate to the remaining book value each period.

VAT calculation: tax = taxable amount × rate; price including VAT = taxable amount × (1 + rate).

Inventory valuation: FIFO assigns oldest costs to goods sold; LIFO assigns newest costs, raising cost of goods sold when prices rise.

Spreadsheet rule: absolute references ($A$1) stay fixed when copied; relative references (A1) shift by the copied offset.

Water quality thresholds for most cultured fish: dissolved oxygen above 5 mg/L, ammonia (NH3-N) below 0.1 mg/L, and temperature within species-specific optimum.

Aquaculture stocking density is expressed as biomass per volume (kg/m³) or per area (kg/m²); exceeding carrying capacity lowers growth and raises disease risk.

Recirculating aquaculture systems (RAS) require mechanical filtration, biofiltration (nitrifying bacteria convert ammonia → nitrite → nitrate), and aeration/oxygenation.

Fish age is estimated from otolith (ear stone) or scale annuli; each ring typically corresponds to one year of growth.

Fishing gear classification: gillnets entangle, trawls tow a cone-shaped net, longlines use baited hooks on a main line, and pots/traps capture by attraction.

Maximum sustainable yield (MSY) occurs near half the carrying capacity (K/2) in the logistic growth model; harvest above MSY depletes the stock.

Cold-chain rule: fresh fish should be held near 0 °C on flake ice; histamine-forming bacteria in scombroid fish multiply rapidly above 4 °C.

Tides: semidiurnal means two high and two low tides per lunar day; spring tides occur at new and full moon when solar and lunar forces align.

Erikson's psychosocial stages: trust vs mistrust (infancy), autonomy vs shame (toddler), initiative vs guilt (preschool), industry vs inferiority (school age), identity vs role confusion (adolescence).

Piaget's cognitive stages: sensorimotor (0–2), preoperational (2–7), concrete operational (7–11), formal operational (11+).

Maslow's hierarchy from base: physiological → safety → belonging → esteem → self-actualization; lower needs generally precede higher ones.

Care-planning cycle: assessment → diagnosis/needs identification → planning → implementation → evaluation, with documentation at each step.

Infection-control standard precaution: hand hygiene before and after contact; gloves for body-fluid contact; mask and eye protection when splash risk exists.

Body temperature regulation: normal core temperature is about 36.5–37.5 °C; hypothermia below 35 °C, fever commonly above 38 °C.

Client confidentiality rule: disclose personal information only with consent or when legally mandated (e.g., imminent danger, notifiable disease).

Vital-sign reference ranges for adults: pulse 60–100 beats/min, respirations 12–20/min, blood pressure around 120/80 mmHg.

Color mixing: additive (RGB, light) primaries are red, green, blue; subtractive (CMY, print) primaries are cyan, magenta, yellow, with black (K) added for depth.

Color harmony rules: complementary colors sit opposite on the color wheel (high contrast); analogous colors sit adjacent (harmonious, low contrast).

Design principles: balance, contrast, emphasis, rhythm, proportion, unity - applied to organize visual elements.

Rule of thirds: placing the subject near the intersections of a 3×3 grid usually yields more dynamic composition than dead-center placement.

Resolution rule: print requires about 300 ppi at final size; screen/web commonly uses 72–96 ppi; image file size grows with the square of resolution.

Vector graphics (SVG, AI) scale without pixelation because they store mathematical paths; raster graphics (JPG, PNG) store a pixel grid and lose quality when enlarged.

CMYK vs RGB workflow: RGB for screens, CMYK for offset/digital print; converting RGB to CMYK can shift saturated colors out of printable gamut.

Typography measure: body text is typically set at 45–75 characters per line for comfortable reading; leading (line spacing) is usually 120–145% of font size.

Macronutrient energy values: carbohydrate 4 kcal/g, protein 4 kcal/g, fat 9 kcal/g, alcohol 7 kcal/g.

Six nutrient classes: carbohydrates, proteins, fats, vitamins, minerals, and water; the first three supply energy.

Balanced plate guidance: about half vegetables/fruit, one quarter protein foods, one quarter grains, plus a dairy or calcium source.

HACCP seven principles: hazard analysis, determine critical control points, set critical limits, monitor, establish corrective actions, verify, and keep records.

Danger-zone rule: perishable food should stay out of 5–60 °C; bacteria multiply fastest near 37 °C, so rapid chilling and thorough reheating (above 75 °C core) are required.

Food label order: ingredients are listed by descending weight; nutrition facts give energy and nutrients per serving or per 100 g.

Maillard reaction (browning between amino acids and reducing sugars) begins around 140–165 °C; caramelization is sugar-only browning at higher temperatures.

Cross-contamination control: separate raw meat from ready-to-eat foods, use distinct color-coded cutting boards, and sanitize surfaces after raw contact.

Tourism system components: origin region, transit route, and destination region; demand is generated at the origin and satisfied at the destination.

Tourism multiplier effect: each unit of tourist spending circulates through the local economy, generating indirect and induced income greater than the initial outlay.

Tourism area life cycle stages: exploration → involvement → development → consolidation → stagnation → decline or rejuvenation.

Sustainable tourism triple bottom line balances economic benefit, socio-cultural integrity, and environmental conservation.

Carrying capacity limits visitor numbers before resource degradation; it is set by physical, ecological, and social thresholds.

Ecotourism principles: minimize impact, build environmental awareness, provide direct financial benefit to conservation and local communities.

Travel-document rule: passports usually need at least six months' validity beyond the return date; visa requirements depend on nationality and destination.

Package tour pricing: total cost = transport + accommodation + meals + guide/agency margin + taxes; per-person price divides total cost by group size.

Kirchhoff's laws: KCL - the sum of currents entering a node equals the sum leaving; KVL - the sum of voltage drops around any closed loop is zero.

Resistors in series add (R = R1 + R2); in parallel, 1/R = 1/R1 + 1/R2, so total resistance is less than the smallest branch.

Capacitor impedance Xc = 1/(2πfC); inductor impedance XL = 2πfL - capacitors block DC and pass high frequencies, inductors do the opposite.

Diode forward bias: conducts when anode is more positive than cathode by about 0.7 V (silicon) or 0.3 V (germanium); reverse bias blocks current.

Digital logic gates: AND outputs 1 only when all inputs are 1; OR outputs 1 when any input is 1; NOT inverts; XOR outputs 1 when inputs differ.

Electrical safety: earth/ground conductor carries fault current, and a residual-current device (RCD) trips at a small imbalance (commonly 30 mA) to prevent electrocution.

Battery energy: Wh = voltage × ampere-hours; series connection raises voltage while parallel connection raises capacity (Ah).

RMS and peak: for a sine wave, V_rms = V_peak ÷ √2 (about 0.707 × peak); average power in a resistive load P = V_rms² / R.

Concrete mix ratio by volume (cement : sand : gravel) commonly runs 1:2:3 for general structural work; lower water-cement ratio raises strength and durability.

Concrete curing: keep moisture and favorable temperature for at least 7 days (28 days for full design strength); strength gain is roughly logarithmic with time.

Rebar cover protects steel from corrosion and provides fire resistance; typical slab cover is 20 mm, beams/columns 30–40 mm depending on exposure.

Slope and drainage: ground should fall away from the building at about 1–2% (1–2 cm per meter) to divert surface water.

Scale drawing: 1:100 means 1 cm on the drawing equals 100 cm (1 m) in reality; area scales by the square of the ratio (1:100 → 1 cm² = 1 m²).

Beam load types: dead load (self-weight and permanent fixtures), live load (occupants and movable items), and environmental loads (wind, snow, seismic).

Mortar and plaster proportions: 1:3 cement-sand for structural mortar, 1:4–1:6 for plaster; higher sand content lowers strength but improves workability.

Safety rule: scaffold platforms require guardrails and toe boards; a fall-arrest harness is mandatory above the height set by local regulations (commonly 2 m).

Stress = Force ÷ Cross-sectional area (σ = F/A); strain = change in length ÷ original length; Young's modulus E = σ/ε in the elastic region.

Torque = Force × perpendicular distance (T = F × r); power transmitted by a rotating shaft P = 2πnT (n in revolutions per second).

Mechanical advantage of a lever = effort arm ÷ load arm; of a pulley system = number of supporting rope segments.

Thermal expansion ΔL = α × L × ΔT; different metals expand at different rates, which is why bimetallic strips bend when heated.

Bearing types: ball/roller bearings carry radial loads and reduce friction; thrust bearings carry axial loads.

Hydraulic press principle (Pascal): pressure applied to a confined fluid is transmitted equally; F1/A1 = F2/A2, so a small piston force can lift a large load.

Fits and tolerances: clearance fit allows relative motion, interference fit creates a press fit for torque transmission, transition fit lies between.

Efficiency = useful output energy ÷ input energy × 100%; losses appear as friction heat, vibration, and noise.

Hierarchy of controls, most to least effective: elimination, substitution, engineering controls, administrative controls, personal protective equipment (PPE).

Safety signs: red = prohibition/fire equipment, yellow = warning, blue = mandatory action, green = safe condition/escape route.

Fire classes and extinguishers: Class A (solids) water; B (flammable liquids) foam/CO2; C (gas) dry powder; electrical fires use CO2 or dry powder, never water.

Incident reporting sequence: secure the scene, provide first aid, report to the supervisor, record in the accident log, then investigate root cause.

Hazard identification uses a risk matrix: risk level = likelihood × severity, guiding whether to eliminate, control, or monitor.

Manual handling rule: keep the load close to the body, bend knees not the back, and avoid twisting while lifting; team-lift loads beyond individual capacity.

Lockout/tagout (LOTO): isolate energy sources, lock and tag, verify zero energy before maintenance, and remove locks only by the person who applied them.

Personal protective equipment selection: head protection for overhead hazards, eye protection for flying particles/chemicals, hearing protection above 85 dB(A) exposure, respiratory protection for airborne contaminants.

Crop rotation with legumes fixes atmospheric nitrogen via Rhizobium symbiosis, cutting synthetic N fertilizer need; alternating deep- and shallow-rooted crops reduces soil compaction and pest buildup.

Photosynthesis net equation: 6CO2 + 6H2O + light energy → C6H12O6 + 6O2; light-dependent reactions occur in thylakoid membranes, the Calvin cycle in the stroma.

Soil pH governs nutrient availability: most field crops favor pH 6.0–7.0; below 5.5 aluminum toxicity and phosphorus lock-up increase, corrected by liming (CaCO3 or Ca(OH)2).

N-P-K labels give percent elemental N, P2O5, and K2O by mass; 100 kg of 20-10-10 supplies 20 kg N, 10 kg P2O5, and 10 kg K2O.

Integrated pest management decision rule: act only when pest counts exceed the economic threshold; rotate modes of action to slow resistance, and prefer biological/cultural controls first.

Grafting joins a scion (fruit-bearing top) to a rootstock (root system); rootstock choice controls vigor, soil-borne disease resistance, and cold tolerance.

Animal breeding: heritability (h²) estimates the share of phenotypic variance that is genetic; selection response R = h² × selection differential S.

Greenhouse transplanting rule: harden seedlings by gradually lowering temperature and water 7–10 days before field setting to reduce transplant shock.

Ohm's law: V = I × R; power P = V × I = I²R = V²/R. In a series circuit current is equal everywhere; in parallel circuits voltage is equal across branches.

Three-phase power: P = √3 × V_L × I_L × power factor for a balanced load; power factor = kW/kVA.

A transformer changes AC voltage by turns ratio V1/V2 = N1/N2; it cannot change frequency and works only on AC.

Gear ratio = driven teeth ÷ driver teeth; a ratio > 1 reduces speed and increases torque proportionally (ignoring losses).

Cutting speed for turning: v = π × D × n / 1000 (v in m/min, D in mm, n in rpm); higher hardness demands lower speed and greater coolant flow.

Bearing clearance and lubrication rule: hydrodynamic lubrication requires a continuous oil film; insufficient film causes metal-to-metal contact and seizure.

PLC scan cycle order: read inputs → execute program → update outputs, repeated cyclically; scan time limits how fast an input change can be detected.

Bearing/steel heat treatment: quenching forms martensite (hard, brittle), then tempering relieves internal stress and restores toughness.

Accounting equation: Assets = Liabilities + Equity; every transaction keeps it balanced (double entry).

Profit = Revenue − Expenses; gross profit = Sales − Cost of goods sold; operating profit also deducts operating expenses.

Break-even quantity = Fixed costs ÷ (Unit price − Unit variable cost); the denominator is the contribution margin per unit.

Current ratio = Current assets ÷ Current liabilities; a value near 1.5–2.0 generally signals adequate short-term solvency.

Depreciation straight-line = (Cost − Residual value) ÷ Useful life; declining balance applies a fixed rate to the remaining book value each period.

VAT calculation: tax = taxable amount × rate; price including VAT = taxable amount × (1 + rate).

Inventory valuation: FIFO assigns oldest costs to goods sold; LIFO assigns newest costs, raising cost of goods sold when prices rise.

Spreadsheet rule: absolute references ($A$1) stay fixed when copied; relative references (A1) shift by the copied offset.

Water quality thresholds for most cultured fish: dissolved oxygen above 5 mg/L, ammonia (NH3-N) below 0.1 mg/L, and temperature within species-specific optimum.

Aquaculture stocking density is expressed as biomass per volume (kg/m³) or per area (kg/m²); exceeding carrying capacity lowers growth and raises disease risk.

Recirculating aquaculture systems (RAS) require mechanical filtration, biofiltration (nitrifying bacteria convert ammonia → nitrite → nitrate), and aeration/oxygenation.

Fish age is estimated from otolith (ear stone) or scale annuli; each ring typically corresponds to one year of growth.

Fishing gear classification: gillnets entangle, trawls tow a cone-shaped net, longlines use baited hooks on a main line, and pots/traps capture by attraction.

Maximum sustainable yield (MSY) occurs near half the carrying capacity (K/2) in the logistic growth model; harvest above MSY depletes the stock.

Cold-chain rule: fresh fish should be held near 0 °C on flake ice; histamine-forming bacteria in scombroid fish multiply rapidly above 4 °C.

Tides: semidiurnal means two high and two low tides per lunar day; spring tides occur at new and full moon when solar and lunar forces align.

Erikson's psychosocial stages: trust vs mistrust (infancy), autonomy vs shame (toddler), initiative vs guilt (preschool), industry vs inferiority (school age), identity vs role confusion (adolescence).

Piaget's cognitive stages: sensorimotor (0–2), preoperational (2–7), concrete operational (7–11), formal operational (11+).

Maslow's hierarchy from base: physiological → safety → belonging → esteem → self-actualization; lower needs generally precede higher ones.

Care-planning cycle: assessment → diagnosis/needs identification → planning → implementation → evaluation, with documentation at each step.

Infection-control standard precaution: hand hygiene before and after contact; gloves for body-fluid contact; mask and eye protection when splash risk exists.

Body temperature regulation: normal core temperature is about 36.5–37.5 °C; hypothermia below 35 °C, fever commonly above 38 °C.

Client confidentiality rule: disclose personal information only with consent or when legally mandated (e.g., imminent danger, notifiable disease).

Vital-sign reference ranges for adults: pulse 60–100 beats/min, respirations 12–20/min, blood pressure around 120/80 mmHg.

Color mixing: additive (RGB, light) primaries are red, green, blue; subtractive (CMY, print) primaries are cyan, magenta, yellow, with black (K) added for depth.

Color harmony rules: complementary colors sit opposite on the color wheel (high contrast); analogous colors sit adjacent (harmonious, low contrast).

Design principles: balance, contrast, emphasis, rhythm, proportion, unity - applied to organize visual elements.

Rule of thirds: placing the subject near the intersections of a 3×3 grid usually yields more dynamic composition than dead-center placement.

Resolution rule: print requires about 300 ppi at final size; screen/web commonly uses 72–96 ppi; image file size grows with the square of resolution.

Vector graphics (SVG, AI) scale without pixelation because they store mathematical paths; raster graphics (JPG, PNG) store a pixel grid and lose quality when enlarged.

CMYK vs RGB workflow: RGB for screens, CMYK for offset/digital print; converting RGB to CMYK can shift saturated colors out of printable gamut.

Typography measure: body text is typically set at 45–75 characters per line for comfortable reading; leading (line spacing) is usually 120–145% of font size.

Macronutrient energy values: carbohydrate 4 kcal/g, protein 4 kcal/g, fat 9 kcal/g, alcohol 7 kcal/g.

Six nutrient classes: carbohydrates, proteins, fats, vitamins, minerals, and water; the first three supply energy.

Balanced plate guidance: about half vegetables/fruit, one quarter protein foods, one quarter grains, plus a dairy or calcium source.

HACCP seven principles: hazard analysis, determine critical control points, set critical limits, monitor, establish corrective actions, verify, and keep records.

Danger-zone rule: perishable food should stay out of 5–60 °C; bacteria multiply fastest near 37 °C, so rapid chilling and thorough reheating (above 75 °C core) are required.

Food label order: ingredients are listed by descending weight; nutrition facts give energy and nutrients per serving or per 100 g.

Maillard reaction (browning between amino acids and reducing sugars) begins around 140–165 °C; caramelization is sugar-only browning at higher temperatures.

Cross-contamination control: separate raw meat from ready-to-eat foods, use distinct color-coded cutting boards, and sanitize surfaces after raw contact.

Tourism system components: origin region, transit route, and destination region; demand is generated at the origin and satisfied at the destination.

Tourism multiplier effect: each unit of tourist spending circulates through the local economy, generating indirect and induced income greater than the initial outlay.

Tourism area life cycle stages: exploration → involvement → development → consolidation → stagnation → decline or rejuvenation.

Sustainable tourism triple bottom line balances economic benefit, socio-cultural integrity, and environmental conservation.

Carrying capacity limits visitor numbers before resource degradation; it is set by physical, ecological, and social thresholds.

Ecotourism principles: minimize impact, build environmental awareness, provide direct financial benefit to conservation and local communities.

Travel-document rule: passports usually need at least six months' validity beyond the return date; visa requirements depend on nationality and destination.

Package tour pricing: total cost = transport + accommodation + meals + guide/agency margin + taxes; per-person price divides total cost by group size.

Kirchhoff's laws: KCL - the sum of currents entering a node equals the sum leaving; KVL - the sum of voltage drops around any closed loop is zero.

Resistors in series add (R = R1 + R2); in parallel, 1/R = 1/R1 + 1/R2, so total resistance is less than the smallest branch.

Capacitor impedance Xc = 1/(2πfC); inductor impedance XL = 2πfL - capacitors block DC and pass high frequencies, inductors do the opposite.

Diode forward bias: conducts when anode is more positive than cathode by about 0.7 V (silicon) or 0.3 V (germanium); reverse bias blocks current.

Digital logic gates: AND outputs 1 only when all inputs are 1; OR outputs 1 when any input is 1; NOT inverts; XOR outputs 1 when inputs differ.

Electrical safety: earth/ground conductor carries fault current, and a residual-current device (RCD) trips at a small imbalance (commonly 30 mA) to prevent electrocution.

Battery energy: Wh = voltage × ampere-hours; series connection raises voltage while parallel connection raises capacity (Ah).

RMS and peak: for a sine wave, V_rms = V_peak ÷ √2 (about 0.707 × peak); average power in a resistive load P = V_rms² / R.

Concrete mix ratio by volume (cement : sand : gravel) commonly runs 1:2:3 for general structural work; lower water-cement ratio raises strength and durability.

Concrete curing: keep moisture and favorable temperature for at least 7 days (28 days for full design strength); strength gain is roughly logarithmic with time.

Rebar cover protects steel from corrosion and provides fire resistance; typical slab cover is 20 mm, beams/columns 30–40 mm depending on exposure.

Slope and drainage: ground should fall away from the building at about 1–2% (1–2 cm per meter) to divert surface water.

Scale drawing: 1:100 means 1 cm on the drawing equals 100 cm (1 m) in reality; area scales by the square of the ratio (1:100 → 1 cm² = 1 m²).

Beam load types: dead load (self-weight and permanent fixtures), live load (occupants and movable items), and environmental loads (wind, snow, seismic).

Mortar and plaster proportions: 1:3 cement-sand for structural mortar, 1:4–1:6 for plaster; higher sand content lowers strength but improves workability.

Safety rule: scaffold platforms require guardrails and toe boards; a fall-arrest harness is mandatory above the height set by local regulations (commonly 2 m).

Stress = Force ÷ Cross-sectional area (σ = F/A); strain = change in length ÷ original length; Young's modulus E = σ/ε in the elastic region.

Torque = Force × perpendicular distance (T = F × r); power transmitted by a rotating shaft P = 2πnT (n in revolutions per second).

Mechanical advantage of a lever = effort arm ÷ load arm; of a pulley system = number of supporting rope segments.

Thermal expansion ΔL = α × L × ΔT; different metals expand at different rates, which is why bimetallic strips bend when heated.

Bearing types: ball/roller bearings carry radial loads and reduce friction; thrust bearings carry axial loads.

Hydraulic press principle (Pascal): pressure applied to a confined fluid is transmitted equally; F1/A1 = F2/A2, so a small piston force can lift a large load.

Fits and tolerances: clearance fit allows relative motion, interference fit creates a press fit for torque transmission, transition fit lies between.

Efficiency = useful output energy ÷ input energy × 100%; losses appear as friction heat, vibration, and noise.

Hierarchy of controls, most to least effective: elimination, substitution, engineering controls, administrative controls, personal protective equipment (PPE).

Safety signs: red = prohibition/fire equipment, yellow = warning, blue = mandatory action, green = safe condition/escape route.

Fire classes and extinguishers: Class A (solids) water; B (flammable liquids) foam/CO2; C (gas) dry powder; electrical fires use CO2 or dry powder, never water.

Incident reporting sequence: secure the scene, provide first aid, report to the supervisor, record in the accident log, then investigate root cause.

Hazard identification uses a risk matrix: risk level = likelihood × severity, guiding whether to eliminate, control, or monitor.

Manual handling rule: keep the load close to the body, bend knees not the back, and avoid twisting while lifting; team-lift loads beyond individual capacity.

Lockout/tagout (LOTO): isolate energy sources, lock and tag, verify zero energy before maintenance, and remove locks only by the person who applied them.

Personal protective equipment selection: head protection for overhead hazards, eye protection for flying particles/chemicals, hearing protection above 85 dB(A) exposure, respiratory protection for airborne contaminants.

Crop rotation with legumes fixes atmospheric nitrogen via Rhizobium symbiosis, cutting synthetic N fertilizer need; alternating deep- and shallow-rooted crops reduces soil compaction and pest buildup.

Photosynthesis net equation: 6CO2 + 6H2O + light energy → C6H12O6 + 6O2; light-dependent reactions occur in thylakoid membranes, the Calvin cycle in the stroma.

Soil pH governs nutrient availability: most field crops favor pH 6.0–7.0; below 5.5 aluminum toxicity and phosphorus lock-up increase, corrected by liming (CaCO3 or Ca(OH)2).

N-P-K labels give percent elemental N, P2O5, and K2O by mass; 100 kg of 20-10-10 supplies 20 kg N, 10 kg P2O5, and 10 kg K2O.

Integrated pest management decision rule: act only when pest counts exceed the economic threshold; rotate modes of action to slow resistance, and prefer biological/cultural controls first.

Grafting joins a scion (fruit-bearing top) to a rootstock (root system); rootstock choice controls vigor, soil-borne disease resistance, and cold tolerance.

Animal breeding: heritability (h²) estimates the share of phenotypic variance that is genetic; selection response R = h² × selection differential S.

Greenhouse transplanting rule: harden seedlings by gradually lowering temperature and water 7–10 days before field setting to reduce transplant shock.

Ohm's law: V = I × R; power P = V × I = I²R = V²/R. In a series circuit current is equal everywhere; in parallel circuits voltage is equal across branches.

Three-phase power: P = √3 × V_L × I_L × power factor for a balanced load; power factor = kW/kVA.

A transformer changes AC voltage by turns ratio V1/V2 = N1/N2; it cannot change frequency and works only on AC.

Gear ratio = driven teeth ÷ driver teeth; a ratio > 1 reduces speed and increases torque proportionally (ignoring losses).

Cutting speed for turning: v = π × D × n / 1000 (v in m/min, D in mm, n in rpm); higher hardness demands lower speed and greater coolant flow.

Bearing clearance and lubrication rule: hydrodynamic lubrication requires a continuous oil film; insufficient film causes metal-to-metal contact and seizure.

PLC scan cycle order: read inputs → execute program → update outputs, repeated cyclically; scan time limits how fast an input change can be detected.

Bearing/steel heat treatment: quenching forms martensite (hard, brittle), then tempering relieves internal stress and restores toughness.

Accounting equation: Assets = Liabilities + Equity; every transaction keeps it balanced (double entry).

Profit = Revenue − Expenses; gross profit = Sales − Cost of goods sold; operating profit also deducts operating expenses.

Break-even quantity = Fixed costs ÷ (Unit price − Unit variable cost); the denominator is the contribution margin per unit.

Current ratio = Current assets ÷ Current liabilities; a value near 1.5–2.0 generally signals adequate short-term solvency.

Depreciation straight-line = (Cost − Residual value) ÷ Useful life; declining balance applies a fixed rate to the remaining book value each period.

VAT calculation: tax = taxable amount × rate; price including VAT = taxable amount × (1 + rate).

Inventory valuation: FIFO assigns oldest costs to goods sold; LIFO assigns newest costs, raising cost of goods sold when prices rise.

Spreadsheet rule: absolute references ($A$1) stay fixed when copied; relative references (A1) shift by the copied offset.

Water quality thresholds for most cultured fish: dissolved oxygen above 5 mg/L, ammonia (NH3-N) below 0.1 mg/L, and temperature within species-specific optimum.

Aquaculture stocking density is expressed as biomass per volume (kg/m³) or per area (kg/m²); exceeding carrying capacity lowers growth and raises disease risk.

Recirculating aquaculture systems (RAS) require mechanical filtration, biofiltration (nitrifying bacteria convert ammonia → nitrite → nitrate), and aeration/oxygenation.

Fish age is estimated from otolith (ear stone) or scale annuli; each ring typically corresponds to one year of growth.

Fishing gear classification: gillnets entangle, trawls tow a cone-shaped net, longlines use baited hooks on a main line, and pots/traps capture by attraction.

Maximum sustainable yield (MSY) occurs near half the carrying capacity (K/2) in the logistic growth model; harvest above MSY depletes the stock.

Cold-chain rule: fresh fish should be held near 0 °C on flake ice; histamine-forming bacteria in scombroid fish multiply rapidly above 4 °C.

Tides: semidiurnal means two high and two low tides per lunar day; spring tides occur at new and full moon when solar and lunar forces align.

Erikson's psychosocial stages: trust vs mistrust (infancy), autonomy vs shame (toddler), initiative vs guilt (preschool), industry vs inferiority (school age), identity vs role confusion (adolescence).

Piaget's cognitive stages: sensorimotor (0–2), preoperational (2–7), concrete operational (7–11), formal operational (11+).

Maslow's hierarchy from base: physiological → safety → belonging → esteem → self-actualization; lower needs generally precede higher ones.

Care-planning cycle: assessment → diagnosis/needs identification → planning → implementation → evaluation, with documentation at each step.

Infection-control standard precaution: hand hygiene before and after contact; gloves for body-fluid contact; mask and eye protection when splash risk exists.

Body temperature regulation: normal core temperature is about 36.5–37.5 °C; hypothermia below 35 °C, fever commonly above 38 °C.

Client confidentiality rule: disclose personal information only with consent or when legally mandated (e.g., imminent danger, notifiable disease).

Vital-sign reference ranges for adults: pulse 60–100 beats/min, respirations 12–20/min, blood pressure around 120/80 mmHg.

Color mixing: additive (RGB, light) primaries are red, green, blue; subtractive (CMY, print) primaries are cyan, magenta, yellow, with black (K) added for depth.

Color harmony rules: complementary colors sit opposite on the color wheel (high contrast); analogous colors sit adjacent (harmonious, low contrast).

Design principles: balance, contrast, emphasis, rhythm, proportion, unity - applied to organize visual elements.

Rule of thirds: placing the subject near the intersections of a 3×3 grid usually yields more dynamic composition than dead-center placement.

Resolution rule: print requires about 300 ppi at final size; screen/web commonly uses 72–96 ppi; image file size grows with the square of resolution.

Vector graphics (SVG, AI) scale without pixelation because they store mathematical paths; raster graphics (JPG, PNG) store a pixel grid and lose quality when enlarged.

CMYK vs RGB workflow: RGB for screens, CMYK for offset/digital print; converting RGB to CMYK can shift saturated colors out of printable gamut.

Typography measure: body text is typically set at 45–75 characters per line for comfortable reading; leading (line spacing) is usually 120–145% of font size.

Macronutrient energy values: carbohydrate 4 kcal/g, protein 4 kcal/g, fat 9 kcal/g, alcohol 7 kcal/g.

Six nutrient classes: carbohydrates, proteins, fats, vitamins, minerals, and water; the first three supply energy.

Balanced plate guidance: about half vegetables/fruit, one quarter protein foods, one quarter grains, plus a dairy or calcium source.

HACCP seven principles: hazard analysis, determine critical control points, set critical limits, monitor, establish corrective actions, verify, and keep records.

Danger-zone rule: perishable food should stay out of 5–60 °C; bacteria multiply fastest near 37 °C, so rapid chilling and thorough reheating (above 75 °C core) are required.

Food label order: ingredients are listed by descending weight; nutrition facts give energy and nutrients per serving or per 100 g.

Maillard reaction (browning between amino acids and reducing sugars) begins around 140–165 °C; caramelization is sugar-only browning at higher temperatures.

Cross-contamination control: separate raw meat from ready-to-eat foods, use distinct color-coded cutting boards, and sanitize surfaces after raw contact.

Tourism system components: origin region, transit route, and destination region; demand is generated at the origin and satisfied at the destination.

Tourism multiplier effect: each unit of tourist spending circulates through the local economy, generating indirect and induced income greater than the initial outlay.

Tourism area life cycle stages: exploration → involvement → development → consolidation → stagnation → decline or rejuvenation.

Sustainable tourism triple bottom line balances economic benefit, socio-cultural integrity, and environmental conservation.

Carrying capacity limits visitor numbers before resource degradation; it is set by physical, ecological, and social thresholds.

Ecotourism principles: minimize impact, build environmental awareness, provide direct financial benefit to conservation and local communities.

Travel-document rule: passports usually need at least six months' validity beyond the return date; visa requirements depend on nationality and destination.

Package tour pricing: total cost = transport + accommodation + meals + guide/agency margin + taxes; per-person price divides total cost by group size.

Kirchhoff's laws: KCL - the sum of currents entering a node equals the sum leaving; KVL - the sum of voltage drops around any closed loop is zero.

Resistors in series add (R = R1 + R2); in parallel, 1/R = 1/R1 + 1/R2, so total resistance is less than the smallest branch.

Capacitor impedance Xc = 1/(2πfC); inductor impedance XL = 2πfL - capacitors block DC and pass high frequencies, inductors do the opposite.

Diode forward bias: conducts when anode is more positive than cathode by about 0.7 V (silicon) or 0.3 V (germanium); reverse bias blocks current.

Digital logic gates: AND outputs 1 only when all inputs are 1; OR outputs 1 when any input is 1; NOT inverts; XOR outputs 1 when inputs differ.

Electrical safety: earth/ground conductor carries fault current, and a residual-current device (RCD) trips at a small imbalance (commonly 30 mA) to prevent electrocution.

Battery energy: Wh = voltage × ampere-hours; series connection raises voltage while parallel connection raises capacity (Ah).

RMS and peak: for a sine wave, V_rms = V_peak ÷ √2 (about 0.707 × peak); average power in a resistive load P = V_rms² / R.

Concrete mix ratio by volume (cement : sand : gravel) commonly runs 1:2:3 for general structural work; lower water-cement ratio raises strength and durability.

Concrete curing: keep moisture and favorable temperature for at least 7 days (28 days for full design strength); strength gain is roughly logarithmic with time.

Rebar cover protects steel from corrosion and provides fire resistance; typical slab cover is 20 mm, beams/columns 30–40 mm depending on exposure.

Slope and drainage: ground should fall away from the building at about 1–2% (1–2 cm per meter) to divert surface water.

Scale drawing: 1:100 means 1 cm on the drawing equals 100 cm (1 m) in reality; area scales by the square of the ratio (1:100 → 1 cm² = 1 m²).

Beam load types: dead load (self-weight and permanent fixtures), live load (occupants and movable items), and environmental loads (wind, snow, seismic).

Mortar and plaster proportions: 1:3 cement-sand for structural mortar, 1:4–1:6 for plaster; higher sand content lowers strength but improves workability.

Safety rule: scaffold platforms require guardrails and toe boards; a fall-arrest harness is mandatory above the height set by local regulations (commonly 2 m).

Stress = Force ÷ Cross-sectional area (σ = F/A); strain = change in length ÷ original length; Young's modulus E = σ/ε in the elastic region.

Torque = Force × perpendicular distance (T = F × r); power transmitted by a rotating shaft P = 2πnT (n in revolutions per second).

Mechanical advantage of a lever = effort arm ÷ load arm; of a pulley system = number of supporting rope segments.

Thermal expansion ΔL = α × L × ΔT; different metals expand at different rates, which is why bimetallic strips bend when heated.

Bearing types: ball/roller bearings carry radial loads and reduce friction; thrust bearings carry axial loads.

Hydraulic press principle (Pascal): pressure applied to a confined fluid is transmitted equally; F1/A1 = F2/A2, so a small piston force can lift a large load.

Fits and tolerances: clearance fit allows relative motion, interference fit creates a press fit for torque transmission, transition fit lies between.

Efficiency = useful output energy ÷ input energy × 100%; losses appear as friction heat, vibration, and noise.

Hierarchy of controls, most to least effective: elimination, substitution, engineering controls, administrative controls, personal protective equipment (PPE).

Safety signs: red = prohibition/fire equipment, yellow = warning, blue = mandatory action, green = safe condition/escape route.

Fire classes and extinguishers: Class A (solids) water; B (flammable liquids) foam/CO2; C (gas) dry powder; electrical fires use CO2 or dry powder, never water.

Incident reporting sequence: secure the scene, provide first aid, report to the supervisor, record in the accident log, then investigate root cause.

Hazard identification uses a risk matrix: risk level = likelihood × severity, guiding whether to eliminate, control, or monitor.

Manual handling rule: keep the load close to the body, bend knees not the back, and avoid twisting while lifting; team-lift loads beyond individual capacity.

Lockout/tagout (LOTO): isolate energy sources, lock and tag, verify zero energy before maintenance, and remove locks only by the person who applied them.

Personal protective equipment selection: head protection for overhead hazards, eye protection for flying particles/chemicals, hearing protection above 85 dB(A) exposure, respiratory protection for airborne contaminants.