VALID Science 8 flashcards
VALID Science 8 · 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 or proposed explanation for an observation, stated before the experiment so that data can either support or refute it.
- Independent variable
- The factor the experimenter deliberately changes or manipulates between trials. It is plotted on the x-axis of a graph of results.
- Dependent variable
- The factor that is measured or observed in response to the independent variable. It is plotted on the y-axis of a graph.
- Control group
- The group in an experiment that receives no treatment or a placebo. It provides a baseline for judging the effect of the treatment.
- Controlled variables
- Factors other than the independent variable that are kept the same across all trials so they cannot affect the outcome.
- Scientific law
- A statement describing a consistent, repeatable pattern in nature, often expressed as a formula, such as Newton's laws or the law of conservation of mass.
- Scientific theory
- A well-supported explanation for a broad set of observations, built from repeated evidence and widely accepted, such as the theory of evolution or plate tectonics.
- Density formula
- Density equals mass divided by volume (D = m/V). Units are grams per cubic centimeter or grams per milliliter; density helps predict whether an object floats.
- Mass versus weight
- Mass is the amount of matter in an object, measured in kilograms and unchanged by location. Weight is the gravitational force on it, measured in newtons.
- Metric length units
- The meter is the base unit of length. One meter equals 100 centimeters and 1000 millimeters; one kilometer equals 1000 meters.
- Volume units
- Volume is measured in liters or cubic centimeters. One liter equals 1000 milliliters, and one milliliter equals one cubic centimeter.
- Repetition and reliability
- Repeating trials and using larger samples reduce the effect of random error, making results more reliable and conclusions more trustworthy.
- Observation versus inference
- An observation is information gathered directly through the senses or instruments. An inference is a logical interpretation or conclusion drawn from those observations.
- Scientific evidence
- Data that are measurable, include units, and can be reproduced by other investigators. Opinion, anecdote, and a single observation do not qualify.
- Data table purpose
- A data table organizes measurements in labeled rows and columns with units, making patterns and calculations such as averages easier to find.
- Bar graph use
- A bar graph compares discrete categories or counts and is appropriate when the independent variable is categorical rather than numerical.
- Line graph use
- A line graph shows how a continuous dependent variable changes across a continuous independent variable, revealing trends, rates, and patterns.
- Conclusion statement
- A conclusion states whether the data supported the hypothesis, cites specific evidence, and notes sources of error or ideas for further testing.
- Measurement accuracy
- Accuracy is how close a measurement is to the true value. Precision is how close repeated measurements are to one another.
- Estimation and scale
- Scientific estimates express size using powers of ten, such as 10³ for one thousand, which makes very large and very small quantities easier to compare.
- Energy definition
- Energy is the ability to do work or cause change, measured in joules. It exists in forms such as kinetic, potential, thermal, chemical, and electrical.
- Kinetic energy
- Kinetic energy is the energy of motion. It increases with mass and increases with the square of speed, so doubling speed quadruples kinetic energy.
- Potential energy
- Stored energy based on position or condition, such as an object raised above the ground or a stretched spring, measured in joules.
- Conservation of energy
- Energy cannot be created or destroyed, only transferred or transformed between forms. The total energy in a closed system stays constant.
- Force definition
- A push or pull on an object, measured in newtons. Forces have both size and direction and can change an object's motion or shape.
- Balanced forces
- Equal forces acting in opposite directions on an object. They cancel out, so the object's motion does not change; it stays still or keeps constant velocity.
- Unbalanced forces
- Forces that do not cancel because one is larger or they do not oppose exactly. They cause acceleration, a change in speed, or a change in direction.
- 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 an unbalanced net force.
- Newton's second law
- Force equals mass times acceleration (F = ma). A larger net force produces greater acceleration; a larger mass produces less acceleration for the same force.
- Newton's third law
- For every action force there is an equal and opposite reaction force acting on a different object, such as a rocket pushing gas backward.
- Friction
- A force that opposes motion between surfaces in contact. It converts kinetic energy into thermal energy and depends on surface type and normal force.
- Speed formula
- Speed equals distance divided by time (s = d/t). Average speed uses total distance and total time, including stops and changes in pace.