Questions from the PastQuestions from the Past

Does weight affect how fast Does weight affect how fast something falls?something falls?

►No! No! ► Fluid friction (Air Fluid friction (Air

Resistance) does!Resistance) does!►Which falls faster an Which falls faster an

elephant or a elephant or a feather with air feather with air resistance.resistance.

► If we take away air If we take away air resistance which will resistance which will fall faster, the fall faster, the elephant or the elephant or the feather?feather?

► They will fall at 9.8 They will fall at 9.8 m/sm/s22

FORCESFORCES

A.A. What is a force?What is a force?1. A force causes a resting object to move, 1. A force causes a resting object to move, and it can accelerate a moving object by and it can accelerate a moving object by changing the object’s speed or direction.changing the object’s speed or direction.

B.B. Measuring a ForceMeasuring a Force1. Ex. A spring scale at the grocery store.1. Ex. A spring scale at the grocery store.

C.C. Unit of ForceUnit of Force1. Newtons = the force that is needed to 1. Newtons = the force that is needed to move 1 Kg at a rate of 1 meter per second.move 1 Kg at a rate of 1 meter per second.2. Named after Sir Isaac Newton.2. Named after Sir Isaac Newton.

How to Draw Forces Acting on How to Draw Forces Acting on ObjectsObjects

►12.1 Forces 12.1 Forces

D.D.Representing ForceRepresenting Force

1. Use arrows: 1. Use arrows:

a. Direction tells you direction of a. Direction tells you direction of force.force.

b. Length tells you how much b. Length tells you how much force.force.

I.I. Sliding FrictionSliding Friction

1. Opposes the direction of 1. Opposes the direction of motion after an object starts motion after an object starts moving.moving.

2. Since Sliding friction is less 2. Since Sliding friction is less than static friction = less force is than static friction = less force is needed to keep the object needed to keep the object movingmoving

Push

Sliding friction

J.J. Rolling frictionRolling friction – opposite – opposite force that acts on a rolling force that acts on a rolling object.object.1. 100 to 1000 times less 1. 100 to 1000 times less than static or sliding friction.than static or sliding friction.

K.K. Fluid frictionFluid friction – friction that – friction that acts on an object in water or acts on an object in water or air.air.

L. L. GravityGravity – acts downward to – acts downward to the center of the earth.the center of the earth.1. Gravity causes objects to 1. Gravity causes objects to accelerate downward.accelerate downward.

M. M. Push force – Push force – force makes force makes you go forwardyou go forward

Draw and Label the forces Draw and Label the forces acting on a box moving to the acting on a box moving to the

left.left.push

Sliding friction

Newton’s 3rd Law, ground pushing up

gravity

An object in motion wants to stay in motion. An object in motion wants to stay in motion. An object at rest wants to stay at rest.An object at rest wants to stay at rest.

►Describe Newton’s Describe Newton’s 11stst Law in Your Own Law in Your Own Words.Words.

When something changes speed When something changes speed or direction it accelerates.or direction it accelerates.

►Describe Newtons Describe Newtons 22ndnd Law. Law.

For every action there’s an For every action there’s an equal and opposite reaction.equal and opposite reaction.

►Describe Newton’s Describe Newton’s 33rdrd Law. Law.

Guy jumps forward, boat goes backward.

A. GravityA. Gravity

D.D.

C.C.

Fluid friction (water) = opposes the velocityFluid friction (water) = opposes the velocityfluid friction (wind) = opposes the velocityfluid friction (wind) = opposes the velocity

A.A.

Physical PropertyPhysical Property

►Any characteristic of a material that Any characteristic of a material that can be observed without changing the can be observed without changing the composition of the material.composition of the material.

►1. Viscosity– The tendency of a liquid to 1. Viscosity– The tendency of a liquid to quit flowing or its resistance to flowing.quit flowing or its resistance to flowing.

►High viscosity = the slower it movesHigh viscosity = the slower it moves

►Syrup has a higher viscosity than waterSyrup has a higher viscosity than water

http://plc.cwru.edu/tutorial/enhanced/lab/visco/intro/intro.htm

► 2. Malleability– The 2. Malleability– The ability of a solid to ability of a solid to be hammered be hammered without shatteringwithout shattering

►Metals are usually Metals are usually malleable. If not, malleable. If not, we wouldn’t have we wouldn’t have gold jewelry or gold jewelry or knives!knives!

►Other materials Other materials break /shatter when break /shatter when hammeredhammered

► 3.Density– Ratio of an 3.Density– Ratio of an object’s mass to object’s mass to volume: Mass/volume volume: Mass/volume (memorize formula!)(memorize formula!)

► Denser object’s sink Denser object’s sink and less dense objects and less dense objects floatfloat

► The box that has more The box that has more balls has more mass balls has more mass per unit of volume. This per unit of volume. This property of matter is property of matter is called density.called density.

►4. Hardness– A material’s ability to 4. Hardness– A material’s ability to resist scratchingresist scratching

►Glass is harder than a penny so glass Glass is harder than a penny so glass can scratch a pennycan scratch a penny

►5. Ductility - The ability of a substance 5. Ductility - The ability of a substance to be stretched; the ability for a metal to be stretched; the ability for a metal to be drawn into wire. to be drawn into wire.

Protons = Positive part of Protons = Positive part of nucleusnucleus

► 1. found in nucleus1. found in nucleus► 2. can tell you the 2. can tell you the

exact elementexact element Example: if you Example: if you

know the element know the element has 10 protons; you has 10 protons; you just find element 10 just find element 10 on the periodic tableon the periodic table

► Used to find atomic Used to find atomic weightweight

Neutrons = no chargeNeutrons = no charge

► Used to find atomic Used to find atomic massmass

► Sometimes the same Sometimes the same element can have element can have different numbers of different numbers of neutrons = ISOTOPESneutrons = ISOTOPES Ex. Carbon 12 has 6 Ex. Carbon 12 has 6

neutrons; 6 protonsneutrons; 6 protons Carbon 14 has 8 Carbon 14 has 8

neutrons; 6 protonsneutrons; 6 protons

► Proton number NEVER Proton number NEVER changeschanges

Electrons = negativeElectrons = negative

► Atomic number = # Atomic number = # of electronsof electrons

► Found outside the Found outside the nucleusnucleus

►Weight almost Weight almost nothingnothing Number of electrons Number of electrons

plays no role in plays no role in calculating the calculating the weight of atoms.weight of atoms.

Valence ElectronsValence Electrons

► Electrons found in Electrons found in the outershellthe outershell

Dot DiagramsDot Diagrams

► Tell you number of Tell you number of valence electronsvalence electrons

► Chlorine has 7 Chlorine has 7 valence electrons valence electrons because it has 7 because it has 7 dots around itdots around it

Atomic number

Number of protons

Number of Electrons

Atomic massProtons + Neutrons

FamiliesFamilies► Each column is called a family.Each column is called a family.► Every family has similar characteristicsEvery family has similar characteristics

The biggest characteristic is valence electronsThe biggest characteristic is valence electrons The number of valence electrons is represented by The number of valence electrons is represented by

Roman numerals above the columnsRoman numerals above the columns Noble gas have 8 valence electrons even though it Noble gas have 8 valence electrons even though it

has an 0has an 0

The Alkali MetalsThe Alkali Metals

►Have 1 valence Have 1 valence electron…extremely electron…extremely reactive.reactive.

► The reactivity The reactivity increases from the increases from the top of Group 1A to top of Group 1A to the bottom.the bottom.

► Li, Na, K, Rb, Cs, FrLi, Na, K, Rb, Cs, Fr

Alkaline EarthAlkaline Earth

► 2 valence electrons2 valence electrons►Differences in Differences in

reactivity among reactivity among the alkaline earth the alkaline earth metals are shown metals are shown by the ways they by the ways they react with water.react with water.

► Be, Mg, Ca, Sr, Ba, Be, Mg, Ca, Sr, Ba, RaRa

The HalogensThe Halogens

► 7 valence electrons7 valence electrons► F, Cl, Br, I, AtF, Cl, Br, I, At►Despite their Despite their

physical differences, physical differences, the halogens have the halogens have similar chemical similar chemical properties.properties.

The Noble GasesThe Noble Gases

►Group 18Group 18► The noble gases are The noble gases are

colorless and colorless and odorless and odorless and extremely extremely unreactive.unreactive.

►He, Ne, Ar, Kr, Xe, He, Ne, Ar, Kr, Xe, RnRn

How Ions are formed!How Ions are formed!

► When an alkali metal or alkaline earth metal When an alkali metal or alkaline earth metal bond with a halogen.bond with a halogen.

► The alkali metals gives a halogen an electron.The alkali metals gives a halogen an electron. The alkali metal becomes a cation (positive)The alkali metal becomes a cation (positive) The halogen becomes an anion (negative).The halogen becomes an anion (negative).

Covalent BondsCovalent Bonds

►When elements When elements share valence share valence electrons equally!!electrons equally!!

Law of Conservation of MassLaw of Conservation of Mass

►Chemical EquationsChemical Equations Reactants on leftReactants on left Products on rightProducts on right

►Number of molecules on left has to Number of molecules on left has to equal number of molecules on rightequal number of molecules on right These equations are said to be balanced.These equations are said to be balanced.

There are six molecules of Carbon on the left, and six on the right.

pH ScalepH Scale

► Tells you how acidic or basicTells you how acidic or basic► AcidsAcids

Citrus fruitsCitrus fruits BatteriesBatteries Stomach juicesStomach juices

► BasesBases Baking SodaBaking Soda Sea WaterSea Water SoapSoap Liquid drain cleanerLiquid drain cleaner

ConductivityConductivity

►The ability to allow electricity/heat to The ability to allow electricity/heat to flow.flow.

►The more conductivity = the more The more conductivity = the more room electrons have to move.room electrons have to move.

►Was a test question a couple of years Was a test question a couple of years ago……ago……

Kinetic EnergyKinetic Energy

► Kinetic is moving Kinetic is moving energy.energy.

► The faster it goes The faster it goes the more energy the more energy hashas

►More temperature = More temperature = more kinetic more kinetic energy.energy.

Potential Energy Potential Energy

►Potential Energy is essentially height!Potential Energy is essentially height! If it is above the ground is has potential If it is above the ground is has potential

energy.energy. The higher it is the more potential energy The higher it is the more potential energy

it hasit has

►Elastic potential energyElastic potential energy If you stretch a substance it has potential If you stretch a substance it has potential

energyenergy

Law of Conservation of Law of Conservation of Energy Energy

►Energy can not be created or Energy can not be created or destroyed.destroyed.

►Energy is just converted from one form Energy is just converted from one form to another.to another.

More Energy TransformationsMore Energy Transformations

Check out how the speed Check out how the speed changes as it goes down the hillchanges as it goes down the hill

This was a test question a couple of years ago….

It asked where would the cart be going the fastest…..it goes the fastest at the bottom!

Other Energy ConversionsOther Energy Conversions

►Energy conversionsEnergy conversions►All forms of energy can be converted All forms of energy can be converted

into other forms.into other forms. The sun’s energy through solar cells can The sun’s energy through solar cells can

be converted directly into electricity.be converted directly into electricity. Green plants convert the sun’s energy Green plants convert the sun’s energy

(electromagnetic) into starches and (electromagnetic) into starches and sugars (chemical energy).sugars (chemical energy).

Fission and FusionFission and Fusion

►Fission is splitting nuclei.Fission is splitting nuclei. Nuclear reactionsNuclear reactions Nuclear bombsNuclear bombs Nuclear powerplantsNuclear powerplants

►Fusion is putting nuclei of atoms Fusion is putting nuclei of atoms togethertogether helium reactions in starshelium reactions in stars

FissionFissionThis is where the most energy is released. Previous test question….

FusionFusion

Wave PropertiesWave Properties

III. Properties of WavesIII. Properties of Waves

A.A. Frequency, Period, and AmplitudeFrequency, Period, and Amplitude1. Frequency = # of cycles in a given 1. Frequency = # of cycles in a given timetime2. Wavelength = is the distance between 2. Wavelength = is the distance between a point on one wave and the same point a point on one wave and the same point on the next cycle of the wave.on the next cycle of the wave.3. Amplitude = how high and low the 3. Amplitude = how high and low the wave goes from the middle.wave goes from the middle.4. The more energy a wave has, the 4. The more energy a wave has, the greater is its amplitudegreater is its amplitude5. 5. http://http://www.ngsir.netfirms.com/englishhtm/TwaveA.htmwww.ngsir.netfirms.com/englishhtm/TwaveA.htm

IV. Behavior of WavesIV. Behavior of Waves

A.A. Reflection = occurs when a wave Reflection = occurs when a wave bounces off a surface it cannot pass bounces off a surface it cannot pass through.through.

1. Reflection does not change the 1. Reflection does not change the speed or frequency of a wave.speed or frequency of a wave.

ex. When you throw a ball at the wall ex. When you throw a ball at the wall it bounces back because it can’t go it bounces back because it can’t go through the wall.through the wall.

B.B. Refraction = the bending of a wave Refraction = the bending of a wave as it enters a new medium.as it enters a new medium.

1. When a wave enters a medium 1. When a wave enters a medium at an angle, refraction occurs at an angle, refraction occurs because one side of the wave because one side of the wave moves more slowly than the other moves more slowly than the other side.side.

C. Diffraction = the bending of a wave C. Diffraction = the bending of a wave as it moves around an obstacle or as it moves around an obstacle or passes through a narrow opening.passes through a narrow opening.

Wave AbsorptionWave Absorption

► Waves can be Waves can be absorbed into the absorbed into the medium.medium. Ex. You do not want Ex. You do not want

waves to bounce around waves to bounce around in a recording studio. in a recording studio. The recording studio The recording studio walls will have carpet on walls will have carpet on them to absorb them to absorb materials.materials.

Modern designs are not Modern designs are not good for recording good for recording studios or music halls.studios or music halls.

ConductionConduction

► The transfer of heat The transfer of heat by direct contact by direct contact between objects or between objects or particles.particles.

ConvectionConvection

►Heat transferred by Heat transferred by the movement of the movement of molecules within a molecules within a substance.substance.

►Movement occurs Movement occurs from warmer areas from warmer areas to cooler areas.to cooler areas.

RadiationRadiation

►Heat transferred Heat transferred through space.through space.

► EXAMPLE: The EXAMPLE: The sun’s rays causing a sun’s rays causing a sunburn.sunburn.

Heat/MovementHeat/Movement► Always from Always from warmerwarmer

to to colder.colder. Examples:Examples:

► heat moves from water heat moves from water to iceto ice

►Heat moves from air to Heat moves from air to waterwater

Adding more ice to a Adding more ice to a glass of cold water will glass of cold water will just make it get cooler just make it get cooler faster and stay cool.faster and stay cool.

Adding more ice does Adding more ice does not make something not make something colder!colder!

Heat and Particle movementHeat and Particle movement

ICE WATER

STEAM

When you add heat particles move faster!

V. Sound and HearingV. Sound and Hearing

A.A. Sound waves are longitudinal Sound waves are longitudinal waves.waves.

B.B. Sound depends on speed, intensity Sound depends on speed, intensity and loudness, frequency and pitch.and loudness, frequency and pitch.

C.C. Speed = how fast sound travelsSpeed = how fast sound travels

D.D. Intensity = how loud is the soundIntensity = how loud is the sound

E.E. Frequency = how high it is or how Frequency = how high it is or how low it is.low it is.

Wave Superimposing on one Wave Superimposing on one AnotherAnother

►http://www.phy.ntnu.edu.tw/ntnujava/ihttp://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=19ndex.php?topic=19