Gifu Entrance Science flashcards

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

Newton's Second Law

The net force on an object equals its mass times acceleration, ΣF = ma. Acceleration points in the direction of the net force and is inversely proportional to mass.

Conservation of Momentum

In a system with no external net force, total momentum before a collision equals total momentum after. Kinetic energy stays constant only in elastic collisions.

Work–Energy Theorem

The net work done on an object equals its change in kinetic energy, W = ½mv² − ½mv₀². Friction doing negative work reduces mechanical energy.

Centripetal Force

The net inward force keeping an object in circular motion, of magnitude mv²/r. It is not an extra force but the resultant of real forces such as tension or gravity.

Snell's Law

At an interface, n₁ sin θ₁ = n₂ sin θ₂, where n = c/v is the refractive index. Light bends toward the normal when entering a denser medium.

Kirchhoff's Loop Rule

The sum of potential differences around any closed circuit loop is zero, expressing energy conservation. Current is the same through components in series.

First Law of Thermodynamics

The change in internal energy equals heat added minus work done by the system, ΔU = Q − W. For an ideal gas, internal energy depends only on temperature.

Carnot Efficiency

The maximum efficiency of a heat engine between two reservoirs is 1 − T_cold/T_hot, using absolute temperatures. No real engine between the same reservoirs exceeds this limit.

VSEPR Theory

Electron pairs around a central atom arrange to minimize repulsion. Lone pairs repel more strongly than bonding pairs, reducing bond angles below idealized values.

Polar vs Nonpolar Molecule

Polar bonds plus an asymmetric shape give a polar molecule, as in water. Symmetric geometry such as linear CO₂ cancels bond dipoles, giving a nonpolar molecule.

Hydrogen Bonding

An attraction between a hydrogen bonded to N, O, or F and a lone pair on a nearby N, O, or F atom. It raises boiling points, as in water.

Ideal Gas Law

PV = nRT relates pressure, volume, moles, and absolute temperature of an ideal gas. At standard temperature and pressure, one mole occupies about 22.4 liters.

Le Chatelier's Principle

When a system at equilibrium is disturbed by concentration, pressure, or temperature change, it shifts to partially counteract that change. Catalysts affect rate, not equilibrium position.

pH and Ka

pH = −log[H⁺]. Strong acids ionize completely, while for weak acids Ka = [H⁺][A⁻]/[HA] describes the extent of ionization in solution.

Redox Oxidation Numbers

Oxidation is a rise in oxidation number from electron loss; reduction is a fall from electron gain. In a balanced redox equation, electrons lost equal electrons gained.

Ester Formation

A carboxylic acid reacts with an alcohol to form an ester plus water, usually with an acid catalyst. The reaction is a condensation and is reversible.

Mitosis vs Meiosis

Mitosis yields two identical diploid cells for growth and repair. Meiosis yields four haploid gametes, with crossing over and independent assortment creating genetic variation.

Mendel's Law of Segregation

The two alleles of a gene separate during gamete formation, so each gamete carries only one. A cross of heterozygotes gives a 3:1 phenotype ratio.

Sex-Linked Inheritance

Genes on the X chromosome show different inheritance in males and females. Males have one X, so a single recessive allele is expressed as the trait.

DNA Base Pairing

Adenine pairs with thymine and guanine with cytosine in DNA. Replication is semiconservative: each new molecule keeps one parental strand.

Negative Feedback

A control mechanism in which a deviation from a set point triggers responses that reverse the deviation, stabilizing conditions such as body temperature and blood glucose.

Energy Flow in Ecosystems

Energy enters as sunlight captured by producers and passes one way through trophic levels. Roughly ten percent transfers to the next level; matter cycles instead.

Natural Selection

Heritable variation plus differential reproductive success changes allele frequencies across generations. Individuals with favorable traits leave more offspring, shifting population traits.

Carrying Capacity

The maximum population size an environment sustains given available resources. Logistic growth levels off at this value, unlike unlimited exponential growth.

Plate Tectonics Boundaries

Divergent boundaries create new crust at ridges; convergent boundaries cause subduction or mountain building; transform boundaries slide laterally, producing earthquakes.

Relative Humidity

The ratio of actual water vapor to the maximum the air can hold at that temperature. It rises as air cools and reaches 100 percent at the dew point.

Kepler's Third Law

The square of a planet's orbital period is proportional to the cube of its semi-major axis, T² ∝ a³. Distant planets therefore orbit more slowly.

Seismic S-Wave Evidence

S-waves cannot pass through liquids, so their absence beyond a certain depth reveals Earth's liquid outer core. P-waves refract through both solids and liquids.

Control Group

In an experiment, the group receiving no treatment or a placebo. Comparing it with the treatment group isolates the effect of the independent variable.

Accuracy vs Precision

Accuracy is closeness to the true value; precision is repeatability among measurements. Systematic errors reduce accuracy, while random errors mainly reduce precision.

Correlation and Causation

A statistical association between two variables does not prove one causes the other. A confounding variable may drive both, so controlled experiments are needed.

Significant Figures

Digits in a measurement that convey its precision. Multiplication and division keep the fewest significant figures; addition and subtraction keep the fewest decimal places.