# Science STAAR 8th grade Spring Benchmark Vocabulary

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### independent variable

The thing you are testing and change; goes on the x-axis; there is only one.

### constants

parts of the experiment must remain the same; there are multiple.

### dependent variable

The result you MEASURE; goes on the y axis; there is only one.

### force

Any push or pull which causes something to move or change its speed or direction; can be BALANCED or UNBALANCED;

### Balanced forces

equal in size and opposite in direction

### unbalanced forces

not equal in size and/or opposite in direction; a net force results.

### Friction

A force that opposes or slows down motion; Caused by the physical contact between moving surfaces; The amount of depends upon the kinds of surfaces and the force pressing the surfaces together; Changes motion into heat.

### Motion

A change in position of an object compared to a reference point

### Speed

The rate of change in position; or distance ÷ time

### Velocity

Speed plus direction

### Acceleration

The rate of change in velocity

speeding up

### Negative acceleration

slowing down (decelerate)

### First Law (Law of Inertia)

An object at rest stays at rest or an object in motion, stays in motion (in the same direction/at the same speed) unless acted upon by an unbalanced force

### Inertia

The tendency of an object to resist any change in its motion

### Second law (Law of Force and Acceleration)

The greater the force, the greater the acceleration, The greater the mass, the greater the force needed for the same acceleration. Calculated by: F = ma

### Third law (Law of Action-Reaction)

For every action force, there is an equal and opposite reaction force. (Forces are always paired)

### Potential Energy

Energy of position

Energy of motion

### Atomic Number

The number of protons

### Atomic Mass

The sum of the number of protons and neutrons

### proton

Positive charge; inside the nucleus- identifies the atom; 1 atomic mass unit

### electron

Negative charge; in electron cloud / orbiting around nucleus- determines reactivity of element; Almost zero mass: 1/1836 amu!

### neutron

Neutral charge; inside the nucleus- just adds mass/weight; 1 atomic mass unit

### nucleus

center of atom; contains protons and neutrons

### electron cloud

outer part of atom; contains electrons

### Periods

tell the number of electron rings

### Group number

number of valence electrons

### Chemical Property

ability of an element or compound to react with another substance.

### H-R Diagram

Shows the relationship between color, temperature, magnitude & size of stars

### Spiral Galaxy

a galaxy with a bulge in center & distinctive spiral arms

### Elliptical Galaxy

a spherical or elongated galaxy

### Irregular Galaxy

any other type of galaxy

### Full moon

all of surface facing Earth is illuminated by the Sun

### New moon

moon is between Earth & Sun, so lit portion is facing away from Earth

### Waxing moon

lit portion of the moon is "growing"

### Waning moon

lit portion of the moon is "decreasing"

### Gibbous moon

larger than ½ of the moon lit

### Crescent moon

smaller than ½ of the moon lit

### Tide

daily rise & fall in ocean water level

### Spring tides

moon and sun pull together = largest tides

### Neap tide

moon and sun pull against each other = weakest tides

### Rotation

spin of object on its axis; responsible for day vs. night

### Revolution

path of one object around another; also called an orbit

energy from the sun

### Weather

condition changes from day to day

### Climate

a region's general pattern of weather over a long period of time.

### Convection

cool air (or water) is more dense than warm, so it sinks, creating currents

### Air mass

A body of air that has similar pressure, temperature, & humidity

### Front

where two air masses meet or collide

### Surface currents

water movement on the surface of oceans caused by: Winds, Continental deflections, & the Coriolis Effect

### Deep ocean currents

water movement of oceans caused by: Temperature differences, Salinity differences, and density

### Current

movement of water in the ocean

### global conveyor belt

Movement of currents is constant and transfers heat from one part of the Earth to another via water.

### Low pressure

cloudy and often rainy conditions

### High pressure

clear and pleasant skies. High means dry...

### Cold fronts

move from poles toward equator- have triangle flags (think icicles)

### Warm fronts

move from equator toward poles- have half circle flags (think rising sun)

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