Praxis Physical Science 5485 flashcards
Praxis Physical Science 5485 · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Hypothesis
- A testable, falsifiable prediction about the relationship between variables, stated before data collection and evaluated against evidence from a controlled experiment.
- Independent variable
- The variable the experimenter deliberately changes or manipulates to observe its effect; it is plotted on the x-axis when graphing cause-and-effect data.
- Dependent variable
- The variable that is measured or observed in response to the independent variable; it is plotted on the y-axis and may change as a result.
- Control group
- A comparison group that does not receive the experimental treatment or receives a placebo, used to isolate the effect of the independent variable.
- Accuracy
- How close a measured value is to the accepted or true value; high accuracy means small systematic error, not necessarily consistent repeated results.
- Precision
- How close repeated measurements are to one another; high precision means small random error, even if all values are shifted away from the true value.
- Percent error
- A measure of accuracy calculated as the absolute difference between measured and accepted values divided by the accepted value, then multiplied by 100 percent.
- Significant figures
- Digits in a measurement that carry meaningful information: nonzero digits, zeros between them, and trailing zeros after a decimal point; leading zeros are not significant.
- Engineering design process
- An iterative cycle of defining a problem, identifying constraints, brainstorming, prototyping, testing, analyzing data, and refining a solution to meet a specified need.
- Scientific theory versus law
- A theory explains why phenomena occur and is supported by extensive evidence; a law describes a consistent relationship or pattern, often mathematically, without explaining the mechanism.
- Newton's first law
- An object at rest stays at rest, and an object in motion stays in motion at constant velocity, unless acted on by a net external force.
- Newton's second law
- The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass, expressed as F = ma.
- Newton's third law
- For every action force, there is an equal and opposite reaction force; the two forces act on different objects and do not cancel each other.
- Conservation of energy
- Energy cannot be created or destroyed, only transformed or transferred; in a closed system, the total energy remains constant, though it may change form.
- Momentum
- The product of an object's mass and velocity (p = mv), a vector quantity; total momentum is conserved in a closed system with no external net force.
- Impulse
- The product of a force and the time interval over which it acts (J = FΔt); impulse equals the change in an object's momentum.
- Wave speed equation
- The speed of a wave equals its frequency multiplied by its wavelength (v = fλ); period is the reciprocal of frequency, T = 1/f.
- Ohm's law
- The current through a conductor is directly proportional to the voltage across it and inversely proportional to its resistance: V = IR, with V in volts, I in amperes, R in ohms.
- Series circuit
- A circuit with a single path for current; the same current flows through every component, voltages add, and total resistance is the sum of individual resistances.
- Parallel circuit
- A circuit with multiple paths; voltage is the same across each branch, branch currents add, and total resistance is less than the smallest individual resistance.
- Refraction
- The bending of light as it passes between media of different refractive indices; Snell's law n₁ sin θ₁ = n₂ sin θ₂ describes the change in direction.
- Atomic number
- The number of protons in an atom's nucleus, which determines the element's identity; in a neutral atom, it also equals the number of electrons.
- Mass number
- The sum of protons and neutrons in an atom's nucleus; it is written as a superscript before the element symbol and differs among isotopes.
- Isotope
- Atoms of the same element with the same number of protons but different numbers of neutrons, giving different mass numbers and sometimes different physical properties.
- Ionic bond
- A chemical bond formed by the electrostatic attraction between oppositely charged ions, typically after a metal transfers one or more electrons to a nonmetal.
- Covalent bond
- A chemical bond formed when two atoms share one or more pairs of valence electrons, commonly between nonmetals, producing discrete molecules or network solids.
- Mole
- The SI amount-of-substance unit; one mole contains 6.022 × 10²³ representative particles, such as atoms, molecules, ions, or formula units.
- Molar mass
- The mass of one mole of a substance in grams per mole; its numerical value equals the formula mass in atomic mass units.
- Limiting reactant
- The reactant that is completely consumed first in a chemical reaction, limiting the amount of product that can form and determining theoretical yield.
- pH
- A logarithmic measure of hydrogen ion concentration: pH = −log[H⁺]; values below 7 are acidic, 7 is neutral, and above 7 are basic.
- Ideal gas law
- The relationship PV = nRT for an ideal gas, where P is pressure, V is volume, n is moles, R is the gas constant, and T is Kelvin temperature.
- Dilution
- The process of lowering a solution's concentration by adding solvent; the moles of solute remain constant, so M₁V₁ = M₂V₂.