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Motion Test
physical science
72
Science
6th Grade
12/05/2010

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Term
motion
Definition
when distance from another object changes
Term
reference point
Definition
a place or object used for comparison to determine if something is in motion
Term
stationary
Definition
something that doesn't move
Term
International System of Units or SI
Definition
system of measurement used by scientists all over the world
Term
meter
Definition
SI unit for length
Term
speed
Definition
distance/time - distance an object travels in a certain amount of time
Term
average speed
Definition
total distance/total time
Term
velocity
Definition
speed with direction example - 50 m/min east
Term
slope
Definition
steepness of a line on a graph = rise/run (y/x)
Term
friction
Definition
general term for the force that one surface exerts on another when they rub against each other
Term
rolling friction
Definition
kind of friction that results when a wheel turns on a surface, objects roll, use ball bearings, wheels
Term
sliding friction
Definition
the kind of friction that results when you rub sandpaper agains wood, surfaces slide, sand on icy path, powder on ballet slippers
Term
fluid friction
Definition
kind of friction that exists between oil and a door hinge, water, air, when a sold moves through a fluid
Term
weight
Definition
measure of the force of gravity on an object
Term
free fall
Definition
state that exists when the only force acting on an object is gravity, unbalanced force
Term
gravity
Definition
force that accelerates objects towards Earth
Term
terminal velocity
Definition
a falling object reaches this when forces of gravity and air resistance are balanced, greatest velocity a falling object reaches
Term
air resistance
Definition
kind of friction that slows a falling object, type of fluid friction
Term
mass
Definition
amount of matter in an object
Term
factors that affect gravitational force between 2 objects
Definition
mass and distance
Term
factors that affect the friction force between 2 surfaces
Definition
how hard the surfaces push together and the types of surfaces involved
Term
how to reduce friction between 2 surfaces
Definition
use a fluid like water or oil or use wheels
Term
how is mass difference from weight
Definition
mass is measure of matter, weight is measure of gravitational force Earth is exerting on you
Term
if free fall is the same, why do some objects fall through the air at a different rate than others
Definition
air resistance - a wadded up piece of paper will drop faster than a sheet of paper - the force of the air keeps the paper in the air longer
Term
object is in motion when
Definition
its distance from a reference point is changing
Term
balanced force
Definition
do not change an object's motion, net force = 0, push or pull, object doesn't move
Term
unbalanced force
Definition
change in object's motion, push or pull, has direction, object will move
Term
newton
Definition
SI unit for force
Term
force
Definition
push or pull
Term
net force
Definition
sum of all forces acting on an object
Term
acceleration
Definition
net force/mass
Term
If you increase the force on an object, its acceleration
Definition
also increases
Term
2 ways to increase acceleration
Definition
increase force and mass
Term
If you increase the mass on an object, its acceleration
Definition
also increases
Term
inertia
Definition
resistance to a change in motion
Term
amount of inertia an object has depends on its
Definition
mass
Term
the work of pulling a box will be
Definition
easier if the person uses a ramp
Term
ramps make work easier by
Definition
exerting smaller input force even though the distance is longer
Term
efficiency of machine
Definition
output work/input work x 100%
Term
ideal mechanical advantage of a ramp is its mechanical advantage without
Definition
friction - never possible so ideal will always be less than 100%
Term
efficiency
Definition
compares the output work to the input work
Term
machine
Definition
device that allows you to do work in a way that is easier
Term
actual mechanical advantage
Definition
mechanical advantage that a machine provides in a real situation
Term
output force
Definition
force the machine exerts on an object
Term
output work
Definition
output force x the output distance
Term
mechanical advantage
Definition
number of times a machine increases a force exerted on it = output force/input force
Term
input force
Definition
force you exert on a machine
Term
input work
Definition
input force x the input distance
Term
ideal mechanical advantage
Definition
mechanical advantage of a machine without friction
Term
work
Definition
force x distance, measured in Nm also called a Joule
Term
joule
Definition
SI unit of work when you exert a force of 1 newton to move an object a distance of 1 meter
Term
power
Definition
the rate at which work is done, equals the amount of work done on an object in a unit of time
Term
inclined plane
Definition
simple machine - flat, sloped or slanted surface - examples are ramps
Term
wedge
Definition
simple machine - thick at one end and tapers at the other (triangle shaped), example is an axe
Term
screw
Definition
simple machine - inclined plane wrapped around a cylinder to form a spiral
Term
lever
Definition
simple machine - rigid bar that is free to pivot, or rotate, on a fixed point. The fixed point of rotation is the fulcrum. Example is a see-saw, prying open a can with a knife or screwdriver, wheelbarrow, scissors, pliers
Term
wheel and axle
Definition
simple machine made of 2 circular or cylindrical objects fastened together that rotate about a common axis - doorknob, steering wheel
Term
pulley
Definition
simple machine - grovved wheel with a rope or cable wrapped around it - flagpole, crane
Term
compound machine
Definition
utilizes 2 or more simple machines
Term
fulcrum
Definition
the fixed point a lever rotates around
Term
energy
Definition
ability to do work or cause change (wind has energy)
Term
kinetic energy
Definition
an object's energy due to its motion
Term
potential energy
Definition
any type of stored energy
Term
gravitational potential energy
Definition
energy that depends on height
Term
elastic potential energy
Definition
energy associated with objects that can be stretched or compressed
Term
factors affecting kinetic energy
Definition
mass and velocity
Term
relation of work and energy
Definition
work is the transfer of energy, when an object does work on another object some of its energy is transferred to that object so work is the transfer of energy.
Term
relation of power to energy
Definition
power is involved whenever energy is being transferred
Term
2 basic kinds of energy
Definition
kinetic and potential
Term
energy transformation
Definition
change from one from of energy to another
Term
law of conservation of energy
Definition
one form of energy is transformed to another, no energy is destroyed in the process
Term
matter
Definition
anything that has mass and takes up space
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