Akita 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 multiplied by its acceleration (F = ma); force and acceleration point in the same direction.

Conservation of momentum

In a system with no external net force, total momentum before an interaction equals total momentum after it, even in inelastic collisions.

Ohm's law

Current through a conductor is proportional to the potential difference across it at constant temperature, giving V = IR.

Snell's law

Relates angles of incidence and refraction through two media: n₁sinθ₁ = n₂sinθ₂, where n is the refractive index.

Archimedes' principle

The buoyant force on a submerged or floating object equals the weight of the fluid that the object displaces.

Wave equation

Wave speed equals frequency multiplied by wavelength (v = fλ); frequency is set by the source and does not change on refraction.

Mole

The amount of substance containing 6.02 × 10²³ particles; moles equal mass divided by molar mass (n = m/M).

pH scale

pH = −log₁₀[H⁺]; values below 7 are acidic, above 7 basic, and each unit represents a tenfold change in hydrogen-ion concentration.

Oxidation and reduction

Oxidation is loss of electrons and an increase in oxidation number; reduction is gain of electrons and a decrease in oxidation number.

Le Chatelier's principle

When a system at equilibrium is disturbed, it shifts in the direction that partially opposes the change in concentration, pressure, or temperature.

Ionic versus covalent bonding

Ionic bonds transfer electrons between metals and nonmetals; covalent bonds share electron pairs, typically between nonmetals.

Molar volume at STP

One mole of any ideal gas occupies about 22.4 litres at standard temperature and pressure (0 °C and 1 atm).

Periodic trend in atomic radius

Atomic radius decreases left to right across a period as nuclear charge grows, and increases down a group as shells are added.

Enzyme function

Enzymes are proteins that lower activation energy for a reaction; each has an optimum temperature and pH and denatures outside them.

Photosynthesis equation

6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂, driven by light energy captured in chloroplasts to store energy in glucose.

Mitosis versus meiosis

Mitosis yields two identical diploid cells for growth; meiosis yields four genetically varied haploid gametes for reproduction.

Monohybrid cross ratio

Crossing two heterozygotes gives a 3:1 phenotype ratio and a 1:2:1 genotype ratio for a trait showing complete dominance.

Negative feedback

A control mechanism in which a deviation from a set point triggers a response that reverses the deviation, maintaining homeostasis.

Prokaryote versus eukaryote

Prokaryotes lack a membrane-bound nucleus and organelles; eukaryotes have a nucleus, mitochondria, and other membrane-bound structures.

DNA transcription and translation

Transcription copies DNA into mRNA in the nucleus; translation at ribosomes reads codons to assemble amino acids into protein.

Plate boundary types

Divergent boundaries create new crust, convergent boundaries cause subduction or mountain building, and transform boundaries produce earthquakes.

Rock cycle

Igneous rock forms from cooled magma, sedimentary from compacted deposits, and metamorphic from existing rock under heat and pressure.

Seismic S-waves

S-waves are transverse seismic waves that cannot travel through liquids, which is why they do not pass through Earth's outer core.

Cause of seasons

Seasons result from Earth's axial tilt changing the angle and duration of sunlight, not from changes in distance from the Sun.

Kepler's third law

The square of a planet's orbital period is proportional to the cube of its semi-major axis (T² ∝ a³).

Lunar versus solar eclipse

A lunar eclipse occurs at full moon when Earth blocks sunlight to the Moon; a solar eclipse occurs at new moon when the Moon blocks the Sun.

Weathering versus erosion

Weathering breaks rock down in place; erosion transports the broken material, and deposition lays it down elsewhere.

Independent variable

The variable the experimenter deliberately changes; the dependent variable is the measured response to that change.

Accuracy versus precision

Accuracy is closeness to the true value; precision is how closely repeated measurements agree with each other.

Control group

A comparison group that does not receive the treatment, used to isolate the effect of the independent variable.

Correlation versus causation

An association between variables does not prove one causes the other, because a confounding variable may affect both.

Random versus systematic error

Random error scatters results unpredictably and averages out with repeats; systematic error shifts all results in one direction.