Honors Physical Science

1. Honors Physical Science Final Exam Review

2. 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

3. Scientific Method • Hypothesis - possible explanation based on preliminary evidence • Theory – a hypothesis/guess that has been tested repeatedly and always found to be true

4. 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

5. 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

6. 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

7. Prefixes and Scientific Notation Scientific NotationShorthand number writing 0.000000459 g = 4.59x 10-7g

8. Vector Quantities • Has magnitude (size) • Has direction • Ex. Force, Velocity, Momentum • Speed = Distance/Time • Velocity = Distance/Time in a given direction!

9. 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.

10. Significant Figures • SIGNIFICANT • All non-zero numbers (1 through 9) • All “trapped” zeros • END and AFTER = at the end of a number AND after the decimal • NOT SIGNIFICANT • 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)

11. Precision vs. Accuracy • Accurate = you’re right! • Precise = a bunch of numbers are close together To evaluate accuracy, you must compare your value to the correct value! • Error = experimental value – accepted value • % Error = (error ÷ accepted value) x 100

12. 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

13. 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!

14. 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

15. 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

16. Related Formulas! • w = mxg • 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

17. 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!

18. Momentum - Impulse • Momentum is the product of Mass and Velocity • Momentum (kgm/s)= Mass (kg) x velocity (m/s) • p = mv • Momentum is Inertia in motion. Impulse = Δp results from Δ in v or mass or both. Greater Force = Greater Δp Ft = Δmv Decrease force by increasing time of impact!

19. 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

20. Collisions Elastic Collisions Inelastic Collision • Objects separate after collision • [pa + pb] before= [pa + pb]after • [mava + mbvb]before = [mava + mbvb]after • Objects stick together after collision • [pa + pb] before = [pa+b]after • [mava + mbvb]before = [(ma + mb) v]after Don’t forget the sign (+ or - ) for direction of velocity! These formulas will NOT be given

21. 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

22. 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!

23. Energy • Energy-the ability to cause change or to do work • Types of energy: • Potential = energy of position. • mxgxh or F xh. • Kinetic = energy of motion • ½ mx v2 • Mechanical Energy = PE + KE • transfer of energy always occurs when work is done!

24. 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!!

25. 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!

26. 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)!

27. Projectile Motion Formulas! • Vertical Displacement dy = 0.5*g*t2 • Horizontal Displacement dx = vix * t

28. 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.

29. 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!

30. 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)

31. 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!

32. Thermal Expansion • Bimetallic Strip • One metal heatsand 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!

33. 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 = kx (q1x 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!

34. 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)

35. 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!

36. Don’t forget your engineer’s triangles!

37. Parallel vs. Series Circuits Series Circuits Parallel 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

38. 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!

39. 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.

40. 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:

41. Wave Calculations • v = λf • Wave speed (m/s) = wavelength (m) * frequency (Hz or 1/s) • Frequency – vibrationsor cycles/second! • Amplitude is directly proportional to Energy! • Speed is inversely proportional to wavelength and frequency!

42. Electromagnetic Spectrum and Light Waves *Know these in order of wavelength and frequency!The larger wavelength the smaller the frequency!

43. 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!

44. 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

45. 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)

46. 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 ≠ electrons • Cation – lost electrons, become positive • Anion – Gain electrons,become negative

47. 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

48. 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

49. 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!

50. 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!