Science GHSGT ReviewScience GHSGT Review

Physical SciencePhysical Science

What is Physical Science?What is Physical Science?

Study of matter and energyStudy of matter and energyStudy of the physical worldStudy of the physical worldOn GHSGT, physics and chemistryOn GHSGT, physics and chemistry

Speed and VelocitySpeed and Velocity

Speed = distance divided by time Speed = distance divided by time

s = d/ts = d/tUnits of speed = m/sUnits of speed = m/sVelocity = speed in a given Velocity = speed in a given directiondirectionExample: Example:

55 mph = speed55 mph = speed55 mph north = velocity55 mph north = velocity

Distance versus Time GraphDistance versus Time Graph

AKA AKA position position versus time versus time graphgraph

Straight lineStraight line represents represents constant constant (uniform) (uniform) speedspeed

AccelerationAcceleration

Acceleration = rate at which velocity Acceleration = rate at which velocity changeschanges

Involves a Involves a change in speed OR directionchange in speed OR direction

a = (va = (vff – v – vii )/ t )/ tUnits of acceleration = m/sUnits of acceleration = m/s22

Example: 0 to 60 mph in 5 seconds Example: 0 to 60 mph in 5 seconds For acceleration to occur a net For acceleration to occur a net

(unbalanced) force must be applied(unbalanced) force must be applied

Distance versus Time Graph Distance versus Time Graph RevisitedRevisited

Non-linear Non-linear graph graph represents represents accelerationacceleration

Parabola = Parabola = constant constant accelerationacceleration

ForcesForces

Force = a push or a pullForce = a push or a pull Net Force = sum of all Net Force = sum of all

forces acting on an forces acting on an objectobject

Free-body diagram Free-body diagram shows all forces with shows all forces with vector arrowsvector arrows

Direction of force = Direction of force = direction of accelerationdirection of acceleration

Friction is a force that Friction is a force that always always opposesopposes motion motion

Determining the Net ForceDetermining the Net Force

Newton’s 1Newton’s 1stst Law of Motion Law of Motion

An object at rest will An object at rest will remain at rest and remain at rest and an object in an object in constant motion will constant motion will remain in constant remain in constant motion unless acted motion unless acted on by an on by an unbalanced force.unbalanced force.

Reason for Reason for seatbeltsseatbelts

Newton’s 2Newton’s 2ndnd Law of Motion Law of Motion

Force = mass x accelerationForce = mass x acceleration

F = maF = ma

Newton’s 3Newton’s 3rdrd Law of Motion Law of Motion

For every action, For every action, there is an equal there is an equal but opposite but opposite reactionreaction

Examples: Examples: Punch a wall, it Punch a wall, it

punches backpunches backRocket propulsionRocket propulsion

GravityGravity

Gravity = attractive force between two objects Gravity = attractive force between two objects that have massthat have mass

Depends on mass and distanceDepends on mass and distance

Effects of Mass and Distance on Effects of Mass and Distance on GravityGravity

MomentumMomentum

Momentum is mass in motion Momentum is mass in motion p = mvp = mv

To change an object’s momentum a To change an object’s momentum a force must be appliedforce must be applied

Conservation of momentum states that Conservation of momentum states that momentum before a collision equals momentum before a collision equals momentum aftermomentum after

Energy and WorkEnergy and Work

The ability to do work The ability to do work Work = Work = transfertransfer of energy by applying a of energy by applying a

forceforce to to movemove an object an object

W = FdW = Fd

where force and distance are in same where force and distance are in same directiondirection

Both work and energy are measured in Both work and energy are measured in JoulesJoules

Examples of Work and No WorkExamples of Work and No Work

Hammer applies Hammer applies a force to move a force to move the nail in the the nail in the same direction = same direction = WORKWORK

Waiter applies a Waiter applies a force upward force upward while the tray while the tray moves forward = moves forward = NO WORKNO WORK

Types of Mechanical EnergyTypes of Mechanical Energy

Kinetic = energy of Kinetic = energy of motion motion

Potential = stored Potential = stored energy due to positionenergy due to position

Conservation of EnergyConservation of Energy

Conservation of EnergyConservation of Energy

Conversion of EnergyConversion of Energy

Motor = converts electrical energy into Motor = converts electrical energy into mechanical energymechanical energyMMotors make fans otors make fans MMove which is ove which is MMechanicalechanical

Generator = converts mechanical energy Generator = converts mechanical energy into electrical energy into electrical energy GGeorgia Power use a eorgia Power use a GGenerator to provide enerator to provide

electricityelectricity

PowerPower

Power = rate at which Power = rate at which work is donework is done

P = W/tP = W/t Measure in WattsMeasure in Watts More work, less time More work, less time

= More Power= More Power Less Work, Long time Less Work, Long time

= Less Power= Less Power

Heat EnergyHeat Energy

Heat can be transferred through:Heat can be transferred through:Conduction = when objects touchConduction = when objects touchConvection = when matter movesConvection = when matter movesRadiation = in the form of wavesRadiation = in the form of waves

Conductors = easily transmit energy Conductors = easily transmit energy Example: metalsExample: metals

Insulators = do not easily transmit energyInsulators = do not easily transmit energyExample: gases such as airExample: gases such as air

LightLight

Light is a form of electromagnetic radiation (EM)Light is a form of electromagnetic radiation (EM) EM spectrum shows the forms of radiation in EM spectrum shows the forms of radiation in

order of increasing frequency and decreasing order of increasing frequency and decreasing wavelengthwavelength

Color of LightColor of Light

We see different colors depending on the We see different colors depending on the frequency of light emitted or reflectedfrequency of light emitted or reflected

This is the reason blue flames are hotter than This is the reason blue flames are hotter than yellow. Blue has a higher frequency so more yellow. Blue has a higher frequency so more energy.energy.

Refraction of LightRefraction of Light Light waves travel Light waves travel

faster in air than in faster in air than in water and slower in water and slower in glass than water.glass than water.

More dense = More dense = slower lightslower light

When light enters a When light enters a different medium, different medium, speed changes and speed changes and it bends.it bends.

Bending of light due Bending of light due to change in speed to change in speed = = REFRACTIONREFRACTION

ElectricityElectricity

Electrons carry a negative charge.Electrons carry a negative charge. Lost electrons = positive chargeLost electrons = positive charge Gained electrons = negative chargeGained electrons = negative charge REMEMBER:REMEMBER:

Like charges repelLike charges repel Opposites attractOpposites attract

An object can be charged through:An object can be charged through: Friction (rubbing two objects together)Friction (rubbing two objects together) Conduction (touching a charged object to an Conduction (touching a charged object to an

uncharged object)uncharged object) Induction (holding a charged object near an Induction (holding a charged object near an

uncharged object)uncharged object)

Electrical CircuitsElectrical Circuits

Current flows in a Current flows in a closedclosed circuit circuit

Ohm’s LawOhm’s Law V = IRV = IR

Two types of circuits:Two types of circuits: SeriesSeries (single path) (single path) ParallelParallel (poly paths) (poly paths)

SERIES

PARALLEL

ElectromagnetElectromagnet

One can make an electromagnet with a nail, One can make an electromagnet with a nail, battery, and wirebattery, and wire

When current flows through the coiled wire, the When current flows through the coiled wire, the nail becomes magnetized.nail becomes magnetized.

Electromagnetic InductionElectromagnetic Induction

Occurs when a current is produced by Occurs when a current is produced by moving a conducting wire through a moving a conducting wire through a magnetic fieldmagnetic field

Fundamental Parts of the AtomFundamental Parts of the Atom Atoms are made of:Atoms are made of:

Protons (+)Protons (+) Neutrons (neutral)Neutrons (neutral) Electrons (-)Electrons (-)

Most of the mass is in the Most of the mass is in the nucleus (protons & nucleus (protons & neutrons)neutrons)

Atomic number = number Atomic number = number of protonsof protons Silver has 47 protonsSilver has 47 protons

Atomic mass = number of Atomic mass = number of protons + neutronsprotons + neutrons Silver has 61 neutronsSilver has 61 neutrons

Periodic TablePeriodic Table

Left of zig-zag line = metalsLeft of zig-zag line = metalsRight of zig-zag line = non-metalsRight of zig-zag line = non-metalsAlong the line = metalloidsAlong the line = metalloidsGroups/Families = columns; go up and Groups/Families = columns; go up and

down down Group number indicates # of valence Group number indicates # of valence

electronselectronsRows/Periods = side to sideRows/Periods = side to side

Period number indicates # of electron Period number indicates # of electron shells/energy levelsshells/energy levels

Groups to KNOWGroups to KNOW

Group 1 = alkali metals (so reactive never Group 1 = alkali metals (so reactive never found uncombined in nature)found uncombined in nature)

Group 2 = alkaline earth metals (less Group 2 = alkaline earth metals (less reactive than alkali but more reactive than reactive than alkali but more reactive than most metals)most metals)

Group 7 (sometimes 17) = halogens (very Group 7 (sometimes 17) = halogens (very reactive non-metals)reactive non-metals)

Group 8 (sometimes 18) = nobel gases Group 8 (sometimes 18) = nobel gases (non-reactive)(non-reactive)

Acids and BasesAcids and Bases pH determines how acidic or basic a solution ispH determines how acidic or basic a solution is pH 1-6 = acidic pH 1-6 = acidic

Acids dissolve to release hydrogen atomsAcids dissolve to release hydrogen atoms Acid of pH 1 is much stronger than acid of pH 7Acid of pH 1 is much stronger than acid of pH 7 Examples: HCl strong, Citric acid weakExamples: HCl strong, Citric acid weak

pH 7 = neutral pH 7 = neutral De-ionized waterDe-ionized water

pH 8-14 = basicpH 8-14 = basic Bases dissolve to release hydroxide ion (OHBases dissolve to release hydroxide ion (OH--)) Base of pH 8 is much weaker than base of pH 14Base of pH 8 is much weaker than base of pH 14

Physical versus Chemical ChangesPhysical versus Chemical Changes

Physical changes are when Physical changes are when no new no new substancessubstances are formed (i.e. phase are formed (i.e. phase changes such as changes such as melting, freezing, boiling, melting, freezing, boiling, condensation, evaporation, sublimationcondensation, evaporation, sublimation))

Chemical changes occur when Chemical changes occur when new new substancessubstances are formed (i.e. are formed (i.e. rusting, rusting, foaming, burningfoaming, burning))

Whether physical change or chemical Whether physical change or chemical change, change, MASS IS ALWAYS MASS IS ALWAYS CONSERVEDCONSERVED

Phase Change DiagramPhase Change Diagram

Radioactive DecayRadioactive DecayALPHA DECAY

BETA DECAY GAMMA DECAY

•Alpha and beta decay result in transformed atom

•Gamma decay results in same atom with release of energy

Half-LifeHalf-Life

Half-life is the decay of some unstable Half-life is the decay of some unstable isotopes at a consistent rate that can be isotopes at a consistent rate that can be calculated.calculated.

For example: Isotope X has a half life of For example: Isotope X has a half life of 100 years, if I have 50 g of Isotope X, how 100 years, if I have 50 g of Isotope X, how much will remain after 100 years? After much will remain after 100 years? After 200 years?200 years?

Good luck! You Good luck! You can can do it!!!do it!!!