TASC Physical Sciences Level 3 flashcards

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

Independent variable

The factor the experimenter deliberately changes or manipulates, such as the amount of fertilizer given to plants, so its effect on the measured outcome can be observed.

Control group

A comparison group that receives no treatment or a standard treatment, allowing researchers to attribute observed changes to the manipulated variable rather than to other causes.

Accuracy versus precision

Accuracy is how close a measurement is to the true value, while precision is how closely repeated measurements agree with one another; a result can be precise yet inaccurate.

Percent error

A measure of measurement accuracy calculated as the absolute difference between measured and accepted values, divided by the accepted value, then multiplied by one hundred percent.

Falsifiable hypothesis

A testable prediction stating a specific relationship between variables that could be shown false by observation or experiment, which is required for a valid scientific claim.

Significant figures

Digits in a measurement that carry meaning about its precision; multiplication and division results keep the fewest significant figures among the inputs used.

Correlation and causation

Two variables changing together is correlation; causation means one actually produces the other, and it requires controlled evidence rather than observation alone.

Scientific notation

A compact way to write very large or small numbers as a coefficient between one and ten multiplied by a power of ten, such as 3.2 × 10^4.

Speed versus velocity

Speed is a scalar giving distance traveled per unit time; velocity is a vector giving displacement per unit time and includes direction of motion.

Acceleration

The rate at which velocity changes with time, calculated as change in velocity divided by elapsed time; it occurs whenever speed or direction changes.

Newton's second law

The net force on an object equals its mass times its acceleration (F = ma); doubling force doubles acceleration, and doubling mass halves it for the same force.

Newton's third law

For every action force there is an equal and opposite reaction force; the pair acts on two different objects, so the forces never cancel on one object.

Weight versus mass

Mass is the amount of matter in an object and stays constant; weight is the gravitational force on that mass, W = mg, and changes with local gravity.

Kinetic energy

The energy of motion, calculated as one-half the mass times the square of the speed (KE = ½mv²); doubling speed quadruples kinetic energy.

Conservation of energy

Energy cannot be created or destroyed, only transferred or transformed between forms; in a frictionless system, total mechanical energy stays constant.

Work and power

Work is force times displacement in the force's direction; power is the rate of doing work, work divided by time, measured in watts.

Conservation of momentum

In an isolated system with no external net force, total momentum before a collision equals total momentum after; momentum is mass times velocity.

Wave equation

Wave speed equals frequency multiplied by wavelength (v = fλ); when a wave enters a new medium its speed and wavelength change while frequency stays constant.

Ohm's law

Current through a conductor equals voltage divided by resistance (I = V/R); increasing voltage raises current, while increasing resistance lowers it.

Atomic number and mass number

Atomic number counts protons and identifies the element; mass number counts protons plus neutrons; isotopes of an element share atomic number but differ in neutrons.

Valence electrons

Electrons in the outermost occupied shell of an atom; they determine bonding behavior, reactivity, and group trends in the periodic table.

Ionic bond

A bond formed when one atom transfers electrons to another, producing oppositely charged ions that attract each other, typically between a metal and a nonmetal.

Covalent bond

A bond formed when two atoms share one or more pairs of electrons, typically between nonmetals; unequal sharing creates a polar covalent bond.

Conservation of mass

In a chemical reaction atoms are rearranged but not created or destroyed, so a balanced equation has the same number of each type of atom on both sides.

Balancing equations

Adjusting coefficients in front of formulas until each element has equal atoms on both sides; subscripts within formulas must never be changed to balance.

Synthesis and decomposition

Synthesis combines two or more reactants into one product (A + B → AB); decomposition splits one reactant into two or more products (AB → A + B).

Acid and base

An acid donates hydrogen ions and has a pH below seven; a base accepts hydrogen ions and has a pH above seven; they neutralize to form salt and water.

Exothermic versus endothermic

Exothermic reactions release energy to the surroundings and feel warm; endothermic reactions absorb energy and feel cool; catalysts speed either type without being consumed.

Plate boundaries

Divergent boundaries create new crust, convergent boundaries cause subduction and mountain building, and transform boundaries produce earthquakes as plates slide past each other.

Rock cycle

The ongoing process in which igneous rock from cooled magma, sedimentary rock from compacted deposits, and metamorphic rock from heat and pressure transform into one another.

Seasons

Seasonal change results from Earth's tilted axis as it revolves around the Sun, which varies the angle and duration of sunlight reaching each hemisphere.

Moon phases

The changing appearance of the Moon caused by the varying angle between Earth, Moon, and Sun; a full moon occurs when the Sun fully illuminates the side facing Earth.