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Science 8th Grade Final!!!!!!!!!!!!!!!!!!

STUDY
PLAY
how is velocity measured?
meters per 2nd
what is mass measured in?
kilograms
what happens to an object when acceleration is negative?
it goes slower
a push or a pull
force
the combination of all the forces acting on an object
net force
2 or more forces exerted on an object are________ if their effects cancel each other and the do not cause a change in the object's motion
balanced forces
if the forces on an object are balanced, the net force is _____
zero
if the forces are _______, their effects dont cancel each other.
unbalanced forces
any time the forces acting on an object are unbalanced, the net force is not zero and the motion of the object changes
...
if the net force acting on an object is zero, the object remains at rest, or if the object is already moving, continues to move in a straight line with constant speed
Newton's first law of motion
the force that brings nearly everything to a stop is ____, which is the force that acts to resist sliding bw 2 touching surfaces
friction
_____is caused by the attraction bw the atom son the 2 surfaces that are in contact
static friction
____ slows down an object that slides... due to the microscopic roughness of 2 surfaces..... produced when the brake pads in a car's brakes rub against the wheels
sliding friction
_____makes a wheel or tire turn... occurs bw the ground and the part of the tire touching the ground... keeps tire from slipping on the ground...
rolling friction
_________ connects force, acceleration, and mass.... an object acted upon by a force will accelerate in the direction of the force
Newton's 2nd Law of Motion
Acceleration Equation =
acceleration (in meters/second) = net force (Newtons)/ mass (in kilograms) ........ a = Fnet/m
gravity's acceleration
9.8 m/s2
F = ma = m * (9.8m/s2)
...
gravitational force bw u and earth
weight
______ is the point in an object that moves as if all the object's mass were concentrated at that point
center of mass
according to _____________, forces always act in equal but opposite pairs... for every action there is an equal but opposite reaction
Newton's 3rd Law of Motion
______ is the force per unit area that is applied on teh surface of an object
PRESSURE
pressure equation =
pressure (in pascal's) = force (in newtons) / area (in meters squared) ....... P = F/A
weight =
weight = mass * acceleration
a ______ is any substance that has no definite shape and has the ability to flow
fluid
the _______ is an upward fprce that is exerted by a fluid on any object in the fluid
buoyant force
why does an object sink?
if the weight of the object is greater than the buoyant force, the net force on the object is downward and it sinks
if the buoyant force is equal to the object's weight, the forces are balanced and the object's float
...
the buoyant force on an object is equal to the weight of the fluid it displaces
Archimedes Principle
______ of a fluid or an object is the mass of the object divided by the volume it occupies
density
density equation
D = m/v.............. density = mass / volume
when a force is applied to a fluid in closed container, the pressure in the fluid increases everywhere by the same amount
Pascal's Principle
a _____ uses a fluid to increase an input force
hydraulic system
when the speed of a fluid increases, the pressure exerted by the fluid decreases
Bernoulli's Principle
the ability to cause change
energy
_____ is the energy an object has due to its motion
kinetic energy
the energy stored in an object bc of its position
potential energy
increases as its temperature increases
thermal energy
the energy stored in chemical bonds
chemical energy
energy carried by light
radiant energy
the energy that is carried by an electric current
electrical energy
atomic nucleus contains energy that can be transformed into other forms of energy
nuclear energy
energy is never created nor destroyed
law of conservation of energy
_____ a device that transforms kinetic energy into electrical energy
generator
contains a set of narrowly spaced fan blades
turbine
an energy source that is used up much faster than it can be replaced
nonrewnewable resource
an energy source that is replinished continually
renewable resource
energy that is safer and cause less harm to the environment.... include solar, wind, and geothermal energy
alternative resources
_______________ is an energy source that cant be used up by humans
inexhaustible resource
a _______ is a device that transforns radiant energy directly into electrical energy
photovoltaic
a measure of the average value of the kinetic energy of the molecules in random motion
temperature
temperature conversion equations
F to C.... C = (5/9)(F-32)
C to F..... F = (9/5)(C) + 32
Kelvin Scale
K = C = 273
the sum of the kinetic and potential energy of all the molecules in an object is the _____ of the object
thermal energy
____ is thermal energy that is transferred from one object to another when the objects are at diffrent temperatures
heat
______ occurs when the particles in a material collide with neighboring particles
conduction
heat transfer by _______ occurs when energy is transferred by electromagnetic waves
radiation
this transfer of thermal energy by the movement of molecules from one part of a material to another
convection
a _____ is any material that easily transfers heat
conductors
amount of heat needed to raise the temperature of 1 kg of that substance by 1C
specific heat
increase in temperature of a body of water caused by adding warmer water
thermal pollution
a device that converts thermal energy into mechanical energy
heat engine
the fuel burns in a combustion chamber inside the engine
internal combustion engine
speed equation
speed (in meters/second) = distance (in meters) / time (in seconds) ......s = d / t
_____ is found by dividing the total distance traveled by the time taken
average speed
the speed of an object at one instant of time is the object's ________
instantaneous speed
an object is the speed of the object and the direction of its motion
velocity
the change in velocity divided by the time it takes for the change to occur
acceleration
acceleration equation
acceleration (in m/s2) = final speed - inital speed / time
tendency of an object to resit a change in its motion
inertia
an object is a measure of how hard it is to stop the object, and it depends on the object's mass and velocity
momentum
momentum is usually symbolized by
"p"
momentum equation
momentum = mass * velocity
the total momentum of objects that collide is the same before and after the collision
law of conservaition of momentum
if you increase an area the pressure will
decrease
PLASMA IS ______
FLUID
what kind of energy comes from the sun?
solar
bond bw atom of a match
chemical
geothermal energy comes from ____
magma