## Physical Science Final Study guide

problem
the purpose of the experiment

hypothesis
proposed solution; guessed answer – if, then statement or I think, because

independent variable
the factor you change in an experiment that causes a change

dependent variable
the measured variable that depends on the value of the independent variable

conclusion
the answer to the problem written as a statement

K H Da B D C M
use this chart to convert metric measurements

motion
a change in an object’s position

distance
how far an object has moved

displacement
how far an object has moved from its original starting place

instantaneous speed
speed at

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any given point

average speed
total distance divided by total time

balanced forces
forces that are equal in size and opposite in direction; they do not move an object and the net force is equal to zero.

unbalanced forces
forces that are unequal in size and the direction is the same; they cause an object to move

velocity
the speed and direction of an object’s motion; EX: 25 mph North

The Law of Conservation of Momentum
any time two or more objects interact they may exchange momentum but the total amount of momentum stays the same-momentum is conserved~p=m x v

Newton’s 1st Law of Motion
an object in motion stays in motion and an object at rest stays at rest until a net force acts upon the object

Newton’s 2nd Law of Motion
Force= mass x acceleration

Newton’s 3rd Law of Motion
Forces always occur in pairs; the forces will always be equal and opposite

friction
a force that opposes motion between two surfaces that are touching each other; it slows down the motion of objects

static friction
friction between two surfaces that are not moving past each other

sliding friction
friction that opposes motion between two surfaces sliding past one another

rolling friction
friction between a rolling object and surface it rolls on

Law of Gravitation
Any two masses exert an attractive force on each other

gravity
one of the four basic forces that gives the universe its structure; the force of gravity depends on the mass and distance between the objects

air resistance
a type of friction that opposes the force of gravity

mass
the amount of matter in an object; stays the same no matter where you are

weight
the force of gravity pulling on a body; changes as gravitational force changes

speed of gravity on Earth
9.8 m/s2

energy
the ability to cause change

three forms of energy
kinetic, potential, mechanical

kinetic energy
energy in the form of motion; 1/2 mass x velocity(2)

potential energy
energy stored in a motionless object that gives it the potential to cause changes

three types of potential energy
elastic (rubber band), chemical (food), and gravitational (book on a shelf)

mechanical energy
the total amount of potential and kinetic energy in a system

Law of Conservation of Energy
Energy may change from one form to another, but the total amount of energy never changes

power
the amount of work done in a certain amount of time; the rate at which work is done; equals work divided by time and is measured in watts

work
the transfer of energy that occurs when a force makes an object move in the direction of the applied force; measured in joules (lifting weights, moving a desk)

the number of times a machine multiplies the effort force; not determined the same for all simple machines, depends on different things

Units for energy, work, and power
energy- joules, work- joules, power- watts

lever
bar that is free to pivot about a fixed point

pulley
grooved wheel with a rope, simple chain, or cable running along the groove

wheel and axle
machine with two wheels of different sizes rotating together

inclined plane
sloping surface that reduces the amount of force required to do work

wedge
inclined plane with one or two sloping sides that pushes things apart

screw
inclined plane wrapped around a cylindrical post

fulcrum
fixed point on a lever; the place where the lever rotates

1st class lever
fulcrum in the middle; see-saw, hammer, scissors

2nd class lever
fulcrum at the end, load in the middle; wheel barrow, car-jack

3rd class lever
fulcrum at the end, effort in the middle; tweezers, baseball bat

temperature
the average kinetic energy of an object’s atoms or molecules

heat
thermal energy that flows from something warm to something cooler

three methods of transferring thermal energy

conduction
direct contact (frying an egg, grilling meat)

convection
currents in liquids or gases (boiling pasta)

no medium required (sunlight, microwave)

electrical insulator
something that resists the flow of electricity (ex: wood)

electrical conductor
something that allows electricity to flow through it easily (ex: copper)

static electricity
the accumulation of excess electric charges on an object

direct current
Electrical current that flows in only one direction through a wire; found in batteries

alternating current
current in which electrons change direction at a regular rate and is used to run appliances

resistance
an electrical device that resists the flow of electrical current; measured in Ohms

voltage
the difference in electrical charge between two points in a circuit; measured in volts

current
a flow of electricity through a conductor; measured in amperes

Ohm’s Law
I=V/R

series circuit
a circuit in which the objects are connected in a single path (holiday lights)

parallel circuit
circuit in which electric current can follow more than one path (house sockets)

magnetic force
interaction between two magnets – like poles repel and unlike attract

magnetic pole
the regions of a magnet where the magnetic force exerted by the magnet is strongest

magnetic domain
groups of atoms with aligned magnetic poles

electromagnetism
the connection between electricity and magnetism; magnetism produced by an electric current

electromagnet
temporary magnet made by passing an electric current through a wire coiled around an iron bar

nuclear fission
the process of splitting a nucleus into two nuclei with smaller masses

nuclear fusion
the process of two nuclei with low masses combining to form one nucleus of larger mass

wave
repeating disturbance or movement that transfers energy through matter or space

mechanical wave
waves that must travel through a medium

electromagnetic waves
waves that do not require a medium to travel through

transverse waves
matter in the medium moves at right angles to the direction the wave travels; made of crests and troughs

compressional waves
matter in the medium moves back and forth in the same direction the wave travels; made of compressions and rarefactions

rarefaction
less-dense region of compressional waves

compression
dense region of compressional waves

reflection
when a wave strikes an object and bounces off

refraction
the bending of a wave caused by a change in its speed as it moves from one medium to another

interference
when two or more waves overlap and combine to form a new wave

diffraction
when an object causes a wave to change direction and bend around it

amplitude
measure of energy carried by a wave

wavelength
distance between one point on a wave to the nearest point like it (crest to crest; compression to compression)

crest
highest point of a transverse wave

trough
lowest point of a transverse wave

doppler effect
change in the apparent frequency of a wave as observer and source move toward or away from each other

opaque
absorbs and reflects light; does not allow light to pass through it

translucent
some light passes through it

transparent
all light passes through it allows you to see through ex. glass

law of reflection
the angle of incidence is equal to the angle of reflection

neon lights
glass tubes filled with neon that produce light from electron collisions

fluorescent lights
When an electric current is passed through a tube, gas inside emits ultraviolet waves that cause a powder to glow

mirror
allows the reflection of an object to be seen; either a virual or real form

lens
transparent material with a curved surface that refracts light rays

convex lens
a curved lens in which the center is thicker than the edges so it converges light to the focal point

concave lens
a lens that is thicker at the edges than in the middle that bends light rays away from one another

convex mirror
a mirror that is curved outward like the back of a spoon; diverges to the focal point

concave mirror
a mirror that is curved inward like the inside of a spoon; converges to the focal point

constant
the parts of an experiment that stay the same

Speed formula
s=d/t

Acceleration formula
a=(final velocity – inital velocity)/time

power formula
power= work/time

work formula
work= force * distance

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