Yamanashi 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

When no net external impulse acts, total momentum m₁v₁ + m₂v₂ stays constant through a collision. In a perfectly inelastic collision the two bodies stick together and share one final velocity.

Faraday's law of induction

A changing magnetic flux through a coil induces an emf equal to −N ΔΦ/Δt. Lenz's law sets the current direction so its magnetic field opposes the flux change that produced it.

Resistors in parallel

Parallel resistors share the same voltage, and their reciprocals add: 1/R = 1/R₁ + 1/R₂. The equivalent resistance is always smaller than the smallest individual resistor.

First law of thermodynamics

The change in internal energy of a gas equals heat added minus work done by the gas: ΔU = Q − W. In an adiabatic process Q = 0, so ΔU = −W.

Snell's law

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

Ideal gas law

PV = nRT relates pressure, volume, moles, and absolute temperature, with R ≈ 8.31 J/(mol·K). At constant temperature, pressure and volume are inversely proportional (Boyle's law).

Mole and Avogadro constant

One mole contains N_A ≈ 6.02×10²³ particles, and n = m/M gives moles from mass and molar mass. One mole of ideal gas occupies about 22.4 L at 0 °C and 1 atm.

pH definition

pH = −log[H⁺], so a tenfold increase in hydrogen ion concentration lowers pH by one unit. At 25 °C, pH + pOH = 14, and pH below 7 is acidic.

Le Chatelier's principle

When a system at equilibrium is disturbed by concentration, pressure, or temperature change, it shifts to partially offset that change. Raising temperature favors the endothermic direction.

Esterification reaction

A carboxylic acid reacts with an alcohol in the presence of a strong acid catalyst to form an ester and water. The reaction is reversible, and removing water drives it toward the ester.

Periodic trends across a period

Moving left to right across a period, atomic radius decreases while ionization energy and electronegativity increase, because nuclear charge grows while electrons enter the same shell.

Meiosis versus mitosis

Mitosis yields two identical diploid cells for growth; meiosis yields four genetically distinct haploid gametes, with crossing over in prophase I creating new allele combinations.

Mendel's law of segregation

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

Photosynthesis overall equation

6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂. Light reactions in thylakoid membranes produce ATP and NADPH, which the Calvin cycle in the stroma uses to fix carbon.

Logistic population growth

Growth slows as population N approaches carrying capacity K, following dN/dt = rN(1 − N/K). The curve is S-shaped, unlike the J-shaped exponential curve.

Natural selection conditions

Evolution by natural selection requires heritable variation, competition for limited resources, and differential reproductive success, producing change in allele frequencies across generations.

Enzyme denaturation

Above an optimum temperature or outside an optimum pH, an enzyme's tertiary structure changes shape. The active site no longer fits the substrate, so reaction rate falls sharply.

P waves versus S waves

P waves are longitudinal and pass through solids and liquids; S waves are transverse and cannot travel through liquids. The S-wave shadow zone shows Earth's outer core is liquid.

Plate boundary types

Divergent boundaries create new crust at mid-ocean ridges; convergent boundaries produce subduction zones and mountain belts; transform boundaries slide horizontally and generate strike-slip earthquakes.

Coriolis effect

Earth's rotation deflects moving air and water: to the right in the Northern Hemisphere and to the left in the Southern. It shapes global wind belts and storm rotation directions.

Kepler's third law

For orbits around the same central body, the square of the orbital period is proportional to the cube of the semi-major axis: T² ∝ a³. Outer planets therefore orbit more slowly.

Apparent versus absolute magnitude

Apparent magnitude measures brightness as seen from Earth, so nearer stars appear brighter. Absolute magnitude is brightness at a standard 10-parsec distance, revealing true luminosity.

Igneous rock formation

Igneous rock forms when magma or lava cools and crystallizes. Slow cooling underground gives coarse-grained intrusive rock, while rapid cooling at the surface gives fine-grained extrusive rock.

Accuracy versus precision

Accuracy is how close a measurement is to the true value; precision is how closely repeated measurements agree. Systematic error hurts accuracy, while random error mainly limits precision.

Independent and dependent variables

The independent variable is deliberately changed by the experimenter, and the dependent variable is measured in response. All other conditions must be held constant as controls.

Significant figures in multiplication

When multiplying or dividing, the result keeps the same number of significant figures as the input with the fewest. In addition, the result keeps the fewest decimal places instead.

Percent error formula

Percent error = |measured − accepted| / accepted × 100, expressing how far a measurement deviates from the true value as a percentage of that value.

Correlation and causation

A statistical association between two variables does not prove one causes the other. A hidden confounding variable may influence both, or the relationship may be coincidental.

Falsifiable hypothesis

A scientific hypothesis must make a prediction that could be shown wrong by observation or experiment. Statements that cannot be tested against data fall outside empirical science.

Control group purpose

A control group receives no treatment or an inactive placebo, providing a baseline. Comparing it with the experimental group isolates the effect of the variable being tested.

Coulomb's law

The electrostatic force between two point charges is F = kq₁q₂/r², with k ≈ 9.0×10⁹ N·m²/C². The force is attractive for opposite charges and repulsive for like charges.