77 terms

# science exam vocab

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Motion
the state in which one object's distance from another is changing
reference point
a place or object used for comparison to determine if an object is in motion
speed
the distance an object travels per unit of time
average speed
the overall rate of speed at which an object moves
instantaneous speed
the speed you are traveling at a single time
velocity
the speed you travel in a certain direction
acceleration
the rat at which someones's velocity cnanges
meter
the SI unit for length
inertia
the tendancy of an object to resist any change
momentum
the product of an objects mass velocity
mass
the amount of matter in an object
weight
the force of gravity on an object
friction
the force that one surface exerts on another when two surfaces rub against each other
static friction
friction that acts on objects that are not moving
gravity
the force that pulls objcts toward each other
rolling friction
the friction acting when an object rolls across a surface
sliding friction
friction that occurs when one solid surface slides over another
fluid friction
friction that occurs as an object moves through a fluid
free fall
the motion of a falling object when the only force acting on it is gravity.
air resistance
the fluid friction experienced by objects falling through the air
terminal velocity
the greatest velocity a falling object can reach
projectile
an object thrown or launched
law of conservation of momentum
a rule that in the absence of outside forces the total momentum of objects that inetract does not change
balanced forces
equal forces acting on an object in opposite directions
newton
the SI unit for force
net force
the overall force on an object when all the indibidual forces acting on it are added together
force
a push or pull exerted on an office
unbalanced forces
forces that produce a nonzero net force
joule
the SI unit for work
power
the rate at which work is done
work
force exerted on an object that causes it to move
machine
a device that makes things easier to do
inclined plane
a simple machine that is a flat, sloped surface
fulcrum
the fixed point around which a lever pivots
wedge
a simple machine which is a moving inclined plane
input force
the force that you put into a machine
output force
the force excerted by a machine
wheel and axle
a simple machine that consists of two attached circular or cylindrical objects that rotate about a common axis, each one with a different radius
pulley
a simple machine that consists of a grooved wheel with a rope or cable wrapped around it
screw
a simple machine that is an inclined plane wrapped around a central cylinder to form a spiral
lever
a simple machine that consists of a rigid bar that picots about a fixed point
compound machine
a devise that combines two or more simple machines
the mechanical advantage that a machine would have without friction
A machine that accually has a possible mechanical advantage
the number of times a machine increases a force exerted on it
efficiency
the percentage of the input work that is converted to output work
pressure
the force exerted on a surface divided by the total area over which the force is exerted
pascal
the SI unit for pressure
fluid
a material that can easily flow
bernoulli's principle
the rule that a stream f fast-moving fluid exerts less pressure than the surrounding fluid
hydraulic device
a system that multiplies force by transmitting pressure from a small surface area through a confined fluid to a larger surface
lift
an upward force
buoyant force
the upward force exerted by a fluid on a submerged object
archimede's principle
the rule that the bouyant force an an object is equal to the weight of the fluid the object displaces
density
the mass contained in an object
barometer
an instrument used to measure pressure
van allen belts
doughnut shaped regions 1,000-25,000 km aboce earth that contain subatomic particles traveling at high speeds`1
aurora
an atmospheric phenomenon consisting of bands of light caused by charged solar particles following the earth's magnetic lines of force
solar wind
a stream of protons moving radially from the sun
compass
a device with a magnetized needle that spins freely
magnetosphere
the magnetic field of a planet
magnetic declination
the difference between the magnetic north and the true north
atom
the smallest particle of an element that has the properties of that element
element
one of about 100 basic materials that make up all matter
nucleus
the core at the center of every atom
proton
a subatomic particle that has a positive charge and that is found in the nucleus of an atom
neutron
a subatomic particle that has no charge and that is found in the nucleus of an atom
electron
a subatomic particle that has a negative charge surrounding the nucleus
magnetic domain
a region in which the magnetic fields of all atoms are lined up in the same direction
temporary magnet
a magnet made from material that easily loses its magnetism
permanent magnet
A magnet that retains its magnetism after being removed from a magnetic field
ferromagnetic material
a material that shows strong magnetic properties
magnet
any material that attracts iron and materials that contain iron
magnetic pole
one of the two ends of a magnet where the magnetism seems to be concentrated
magnetic force
a force produced when magnetic poles interact
magnetic field
the region around a magnet where the magnetic force is exerted
magnetic field lines
Invisible lines that map out the magnetic field around a magnet