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

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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

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