HONORS PHYSICAL SCIENCE

Final Exam Review

Scientific Method

An orderly method for gaining, organizing, and applying new knowledge

Observation – 2 types Qualitative – describes qualities of

object/event Ex. Color, shape, other adjectives

Quantitative – NUMBERS! Ex. Mass, height, density, frequency

Scientific Method

Hypothesis - possible explanation based on preliminary evidence

Theory – a hypothesis/guess that has been tested repeatedly and always found to be true

Experimental Design

Experiment - evaluates alternative hypotheses Control group

You KNOW the expected outcome Helps determine if experiment ran

correctly Experimental groups

Isolate variable(s) being tested

Experimental Design

Independent Variable (IV)- variables purposefully changed or manipulated; X-axis

Dependent Variable (DV) - variable that may respond to change in Independent Variable; what you measure; Y-axis

Measurements

Metric System Based on units of 10 Used internationally and always in science Base Units:

Meter = length Liter = volume Gram = mass Kelvin = temperature Ampere = current Newton = Force

Prefixes and Scientific Notation

Mega KiloHect

oDec

a Base Unit Deci Centi Milli Micro Nano Pico

(M) (k) (h) (da)

Liter (L)Gram (g)

Meter (m) (d) c (m) ( )m (n) (p)

1000000 1000 100 10 1 1/10 1/100

1/1000

1/1000000

1/1x109 one

billionth

1/1x1012

one trillionth

Scientific NotationShorthand number writing

0.000000459 g = 4.59 x 10-7 g

Vector Quantities Has magnitude (size) Has direction Ex. Force, Velocity,

Momentum

Speed = Distance/Time Velocity = Distance/Time in a given

direction!

Mass – the amount of matter in an object Measured in g, kg, etc.

Volume – the amount of space and object takes up Measured in mL, L, cm3 etc.

Density = mass/volume Units g/cm3 or kg/L or g/mL etc.

Significant Figures

SIGNIFICANT1. All non-zero numbers (1 through 9)2. All “trapped” zeros3. END and AFTER = at the end of a number AND after the

decimal NOT SIGNIFICANT1. Place holder zeros

Multiplying & dividing - answers must contain the same number of significant figures as in the number that has the least amount of significant figures

Adding & subtracting - answers must contain the same number of digits as in the number with the greatest uncertainty (least number of decimal places)

To evaluate accuracy, you must compare your value to the correct value!

Error = experimental value – accepted value

% Error = (error ÷ accepted value) x 100

Accurate = you’re right!

Precise = a bunch of numbers are close together

Precision vs. Accuracy

Motion

Galileo Developed concept of inertia Objects fall at the same rate – SAME

ACCELERATION! Ramp – in the absence of friction ball

should reach same height

Newton’s 1st Law

Inertia - Objects at rest tend to remain at rest.

Moving objects tend to remain moving

Mass is alsoa measure of inertia!

Forces

Net Force – combination of all forces that act on an object.

Mechanical equilibrium : ∑ F = 0 The sum of the forces on the object are

zero – the object will continue doing what it is already doing

Static Equilibrium – object is at rest Dynamic Equilibrium - An object moving at

constant velocity

Newton’s 2nd Law

Force = Mass x Acceleration F = ma

Force measured in N Mass measured in kg Acceleration in m/s2

Force is directly proportional to acceleration

Related Formulas!

w = m x g Weight = mass x gravity g = acceleration due to gravity gearth= -10m/s2

a = (vf – vi)/t or a =Δv/t v = vi + at

speed of a falling object is vy = vyi + gt d= ½ at2

For a falling object d= ½ gt2

Newton’s 3rd Law

Law of Action-Reaction: Forces occur in pairs. Whenever one object exerts a force on the other, the other exerts a force equal and opposite to the first. Action and Reaction Forces ALWAYS act on

different objects Cannot have one without the other!

Momentum - Impulse

Momentum is the product of Mass and Velocity Momentum (kgm/s)= Mass (kg) x velocity

(m/s) p = mv Momentum is Inertia in motion.

Impulse = Δ p results from Δ in v or mass or both.

Greater Force = Greater Δ p

Ft = Δ mvDecrease force by increasing time of impact!

Law of Conservation of Momentum No change in momentum can occur

unless an outside force acts The net momentum before a collision will

equal the net momentum after! Go to:

http://moourl.com/collision

Collisions

Objects separate after collision

[pa + pb] before= [pa + pb]after

[ma va + mb vb]before = [ma va + mb vb]after

Objects stick together after collision

[pa + pb] before = [pa+b]after

[ma va + mb vb]before = [(ma + mb) v]after

Elastic Collisions Inelastic Collision

Don’t forget the sign (+ or - ) for direction of velocity!

These formulas will NOT be given

Work and Power

W = F * d Work = Force * Distance

Work measured in Joules, Force in Newtons, distance in meters

P = w/t Power = work / time

Power measured in watts, work in Joules, time in secs

Machines

Machines – Work in = Work out Wi = Wo Fi*di = Fo*do

Efficiency – how effective the machine is, how much energy is lost Efficiency = Wo/Wi

Efficiency = Fo*do/Fi*di Formula NOT given!

Energy

Energy-the ability to cause change or to do work

Types of energy: Potential = energy of position.

m x g x h or F x h. Kinetic = energy of motion

½ m x v2

Mechanical Energy = PE + KE

• transfer of energy always occurs when work is done!

Law of Conservation of Energy

Energy is neither created nor destroyed it simply changes forms Lost as heat Changes from KE to PE

Remember Roller Coaster and Pendulum Problems

PE converted to KE and vice versa!!

Newton’s Universal Law of Gravitation

Force and mass directly proportional

Force and distance follow the inverse square rule! Double the

distance = ¼ the force!

Projectile Motion

projectiles travel with a parabolic trajectory due to the influence of gravity,

An object thrown up will return to the ground at the same speed (opposite direction)!

Projectile Motion Formulas!

Vertical Displacement

dy = 0.5*g*t2

Horizontal Displacementdx = vix * t

Thermal Energy & Heat

Thermal Energy - The Total E (PE & KE) of all the atoms and molecules in a substance. What has more

thermal energy a cup of coffee or the ocean?

Heat is the movement of Thermal Energy

Thermal E always flows from Warmer to

cooler object.

Specific Heat Capacity

Specific heat capacity- The quantity of heat required to change the temperature of a unit mass (g) of the substance by 1 degree.

Water- high specific heat capacity. Needs a lot of heat to increase temp &takes long time to cool down (release E)

Sand will heat up and cool off much faster than water!

Heat Calculations

H or q = mcΔT H or q = heat (J) m = mass of sample(g) C = specific heat (J / g °C)

*Specific Heat of Water CH2O= 4.18 J/g°C

Δt = change in temperature (°C)

Mixed T = [m1t1+m2t2]/total mass [mass of object 1 * temperature of object 1 +

mass of object 2 * temperature of object 2] / (mass 1 + mass 2)

Heat Transfer

Conduction- transfer of heat E by the collisions between particles in a substance. ( especially solids!) Metals are good conductors due to ability to

loose electrons! Convection- transfer of heat E by the

motion of fluids. Radiation - transfer of heat by means of

electromagnetic radiation. How heat energy travels to earth!

Thermal Expansion

Bimetallic Strip One metal heats

and expands faster than the other

Metal Ring Particles expand when heated The diameter of the hole will increase

Phase Changes As heated (energy added) Solid Liquid

Gas Density decreases!

Electricity

Charge - Measured in Coulombs (C) 1 Coulomb represents a HUGE amount of charge!

p+ = 1.602 x 10-19 C e- = -1.602 x 10-19 C

Coulomb’s Law:

FE = k x (q1 x q2) ÷ r2

k = 9 x 109 Nm2/C2

*Same rules as Newton’s Universal Law of gravitation, replace mass with charge!

Current – the flow of charge, or electrons in one direction, (-)(+). Measured in Amperes (Amps, A) 1 Amp = 1 Coulomb per second

Magnetism is closely related to Electricity!

Voltage (V) – a measure of the difference in electrical potential between two parts of a circuit, or the joules of electrical work done per second (Watts) by the current.

Voltage is therefore…

Watts ÷ Amps, or…Joules (PE) ÷ Coulombs (charge)

Resistance - a measure of how strongly a wire or other substance resists current flowing through it. conductors are low resistance materials, electrical flow is

fast insulators are high resistance materials, electrical flow is

slow

Resistance is measured in OHMS, represented by Greek symbol omega (Ω).

OHMS LAW: Current (I) = voltage (V) /resistance (R)

Power = V * I Measured in Watts!

Don’t forget your engineer’s triangles!

Parallel vs. Series Circuits

Only one path through which e- flow.

(I) is the same at all points in the circuit.

(I) & (R) in a Series Circuit: R in a series circuit = sum of R

for individual devices. R for the wire is TINY so we

ignore it…Rtotal = R1 + R2 + R3…

Kirchhoff’s Law: the sum of all V drops in a system must be equal to the V battery.

Vtotal = V1 + V2 + V3…

More than one path through which e- flow; branch.

(I) splits at one or more branches

(I) & (V) in a Parallel Circuit: Kirchhoff’s Law… I in a parallel circuit = sum of

I for individual branches.Itotal = I1 + I2 + I3…

V is the same in every branch!

Rtotal = Vtotal/Itotal

Series Circuits Parallel Circuits

Waves

Wave -a disturbance or vibration that transfers energy through matter or space.

Sound- waves require a medium (solid,liquid,gas – faster through more dense material!) in which to travel . NO Medium = NO sound

Light – Waves can pass through many materials. Doesn’t require a medium Can travel through space. PURE Energy!

Wave Interactions

Reflection – wave bounces and goes in a new direction. Angle of incidence equals angle of reflection!

Refraction – the wave bends as it passes into and through the object due to a change in speed

Diffraction – The wave bends around an object or through holes in the object. More diffraction occurs through smaller openings!

Absorption – The wave is absorbed and disappears.

Sound Waves

Resonance - Result of forced vibrations in an object when the applied frequency matches the natural frequency of the object

Interference – the ability of waves to interact with each other resulting in increased or decreased effect – i.e. sounds cancel each other out

Doppler effect:

Wave Calculations

v = λf Wave speed (m/s) = wavelength (m) *

frequency (Hz or 1/s) Frequency – vibrations

or cycles/second! Amplitude is directly

proportional to Energy! Speed is inversely proportional to

wavelength and frequency!

Electromagnetic Spectrum and Light Waves

*Know these in order of wavelength and frequency!The larger wavelength the smaller the frequency!

Light Waves

Light color is determined by wavelength or frequency Light Brightness is determined by energy or

amplitude Light is additive:

Red and Blue make Magenta

Blue and Green make Cyan

Red and Green make Yellow

Complementary colors addcreate white light!

Classification of Matter

Mixtures separated based on physical properties Heterogeneous – variable composition, ex. Colloid Homogeneous – ex. solution (know solute and solvent)

Elements on periodic table Compounds – elements in fixed number ratio,

cannot be separated by physical means

Chemistry – Periodic Table & Elements

Groups are VERTICAL (#1-18) Periods are HORIZTONAL (#1-7) give Energy Level

METALS to the left NONMETALS to the right METALLOIDS the steps (middle) NOBLE GASES group #18

Atomic number: # p+ in nucleus,above symbol

Average atomic mass: amu or g/mole, below symbol

Mass Number = protons + neutrons # of neutrons = mass number – atomic number

(protons)

Isotopes and Ions

Isotopes - Atoms of the same element that differ in number of neutrons

If you change the protons, you change the element! Protons determine the element!

Ion - charged particle, protons ≠ electronsCation – lost electrons,

become positiveAnion – Gain electrons,

become negative

Electrons

Exist in energy levels Indicated by period (row) of PT More energy levels the larger the

atom Valence electrons - the

electrons on the outer most energy level and are directly responsible for the chemical properties of the element (involved in bonding) Lewis Dot Structures Atoms “want” full outermost

energy level

Bonding and Electronegativity Ionic Bond –

One atom donates and the other gains electrons

Results in opposite charges Atoms attracted to

eachother

Covalent bond – sharing of valence electrons between 2 atoms Forms enough to fill its outer

electron shell

Polar Covalent Compounds Based on

electronegativities Attraction of atom to electrons Increase left to right and bottom

to top of PT Resulting in slight negative

and slight positive charge of molecule

Fluids

Buoyancy – a measure of the upward force a fluid exerts on an object that is immersed – Dependent on DENSITY!

Archimedes Principle – buoyant force is equal to the weight of the fluid displaced by the object.

Volume of displaced fluid must equal the volume of the object!

Fobject = Fb object floats (equal D) Fobject < Fb object floats (more

above, less below – lower D) Fobject > Fb object sinks (higher

D)

Pressure Increase in speed

of fluid = acceleration = Force = increased pressure!

Pressure dependent on depth only – The deeper the

object the more pressure it experiences!

Final Exam

Tuesday June 15 9:30 – 11:00 in room D25

Bring a NON-GRAPHING Calculator You may not share!

Review Party Thursday After School!