NYS Grade 8 Science flashcards
NYS Grade 8 Science · 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.
- Density
- Mass per unit volume, calculated as density = mass / volume. An object sinks in a fluid when its density is greater than the fluid's density and floats when it is lower.
- Newton's Second Law
- The net force on an object equals its mass times its acceleration (F = ma). For a fixed force, doubling the mass halves the acceleration.
- Kinetic Energy
- The energy an object has because of its motion, calculated as KE = 0.5 x mass x speed squared. It increases with mass but rises with the square of speed.
- Balanced Forces
- Equal forces acting in opposite directions on the same object, giving zero net force. Balanced forces do not change motion, so the object stays at rest or keeps a constant velocity.
- Atomic Number
- The number of protons in an atom's nucleus. It identifies which element the atom is, and in a neutral atom it equals the number of orbiting electrons.
- Conservation of Mass
- In a closed system, matter is neither created nor destroyed during a chemical reaction. The total mass of the reactants equals the total mass of the products.
- Wave Speed Equation
- Wave speed equals frequency multiplied by wavelength. Frequency is the number of waves passing a point each second, measured in hertz.
- Conduction
- Transfer of thermal energy through direct contact, as fast-moving particles collide with slower ones and pass energy along. It occurs mainly in solids and always flows from warmer to cooler regions.
- Series and Parallel Circuits
- In a series circuit all components share one path, so a break stops the current everywhere. In a parallel circuit components sit on separate branches and keep working independently.
- Chloroplast
- A plant cell organelle containing chlorophyll that captures light energy. It is the site of photosynthesis, where carbon dioxide and water are converted into glucose and oxygen.
- Mitochondria
- Organelles that release usable energy through cellular respiration, combining glucose with oxygen to produce ATP, carbon dioxide, and water. Cells with high energy demands contain many of them.
- Photosynthesis
- The process in chloroplasts where plants use light energy, carbon dioxide, and water to make glucose and release oxygen, storing the captured energy in chemical bonds.
- Mitosis
- Cell division that produces two daughter cells with the same number of chromosomes as the parent cell. It is used for growth, repair, and asexual reproduction.
- Meiosis
- Cell division that produces gametes containing half the chromosome number of the parent cell. It generates genetic variation through crossing over and independent assortment of chromosomes.
- Natural Selection
- The process by which individuals with inherited traits better suited to their environment survive and reproduce more often, so those traits become more common in later generations.
- Decomposers
- Organisms such as fungi and bacteria that break down dead plants, animals, and wastes, releasing nutrients into the soil so they can be reused by producers.
- Energy Pyramid
- A diagram showing energy flow between trophic levels. Only about ten percent of the energy at each level passes upward; the rest is lost mostly as heat.
- Outer Core
- The liquid layer of molten iron and nickel between the mantle and the solid inner core. Its circulating currents generate Earth's magnetic field.
- Divergent Boundary
- A plate boundary where two plates move apart and magma rises to fill the gap, forming new crust. Mid-ocean ridges and rift valleys are typical features.
- Subduction
- The process where a denser oceanic plate sinks beneath an overriding plate at a convergent boundary, producing deep-sea trenches, volcanoes, and earthquakes.
- Rock Cycle
- A model describing how igneous, sedimentary, and metamorphic rocks transform into one another through melting, cooling, weathering, erosion, compaction, and heat and pressure.
- Earth's Axial Tilt
- Earth's axis is tilted about 23.5 degrees from the vertical. This tilt makes sunlight strike the hemispheres at different angles during the year, causing the seasons.
- Rotation versus Revolution
- Rotation is a planet spinning on its axis, taking about 24 hours for Earth and causing day and night. Revolution is orbiting the Sun, taking about 365.25 days.
- Weather versus Climate
- Weather is the short-term condition of the atmosphere at a place and time. Climate is the long-term average pattern of weather for a region, usually measured over 30 years.
- Greenhouse Effect
- Greenhouse gases such as carbon dioxide and water vapor absorb outgoing infrared radiation and re-emit it, warming Earth's surface. Increasing these gases raises average global temperature.
- Criteria
- The requirements a design must satisfy to count as successful, such as supporting a specified load, costing less than a set amount, or lasting a certain number of uses.
- Constraint
- A limitation placed on a design, such as budget, available materials, time, safety rules, or maximum size. Constraints restrict which solutions are possible.
- Prototype
- An early working model built to test a design idea and collect data before final production. Prototypes are usually revised several times as test results come in.
- Trade-off
- A compromise in which improving one feature of a design makes another feature worse, such as building a lighter bridge that can carry less weight.
- Controlled Variable
- A factor kept the same in every trial of an experiment so that only the tested variable can affect the outcome.
- Independent Variable
- The factor the experimenter deliberately changes between trials. It is plotted on the horizontal axis, and each level defines a separate test group.
- Iteration
- Repeating the design cycle of building, testing, and revising, using data from each prototype to improve the next version until the criteria are met.