2 Heat Heat is the flow of energy from a cold object to a warmer one. Heat can be transferred by convection, conduction, or radiation
3 Transfer of heat Conduction- Transfer of heat through direct contact Convection- Heat transfer through hot particles rising and cool particles fallingRadiation- Hot particles moving away from a reaction (like a fire).
5 Heat in ReactionsEndothermic reactions absorb heat from surroundings. Examples: melting ice, evaporating liquidExothermic reactions give off heat. Examples: fire/combustion, condensation of liquids
6 Potential and Kinetic Energy Kinetic energy is energy of motionWhen an object is in a high place it has potential energy because of gravityWhen it gains speed as it falls it converts potential energy to kinetic energy.Photo: University of Richmond
7 Chemical EnergyChemical energy is potential energy that could be converted to other types or energy by chemical reactionChemical energy of food can be converted to kinetic energy (movement) by cells in the bodyCombustible materials contain chemical energy that is given off when they burn
8 Photo: TheDailyNathan Mechanical EnergySum of potential and kinetic energyRemains constant: potential energy is converted to kinetic energy and back.Photo: TheDailyNathan
9 Sources of Energy: The Sun Heat energy radiates from sun and is absorbed in solar panelsMethod of energy production that reduces pollutionSustainable, but reliant on sunlight
10 Sources of Energy: Fossil Fuels Oil, Coal and Natural Gas are mined or drilled and burnt, producing energyFossil Fuels may not be sustainable because there is a finite amountFossil fuels produce pollution
11 Sources of Energy: Nuclear Splitting an atom (nuclear fission) gives off heat in a reaction and the energy is harnessedSustainable, but does produce some nuclear wasteThreat of accidents (Chernobyl/Fukushima)
12 Waves Waves transfer energy Electromagnetic waves transfer energy by vibration of electric and magnetic fieldsWater waves transfer energy by moving particles of waterSound waves are movement of particles transmitting sound
13 Parts of a Wave Wavelength: Distance between waves Amplitude: Height of wavesFrequency: How many waves occur in a time frameHigher wavelength means lower frequency.
15 Forces in PhysicsSpeed: Distance traveled in a period of time (magnitude of velocity)Velocity: Speed moved in a directionAcceleration: rate of increase of velocityMomentum: mass of an object times the velocity. A large object has more momentum than a small one moving at the same velocity
16 Collisions Collisions are a transfer of momentum When vehicles in motion collide, a change in momentum of one vehicle is met by a change in momentum of the other vehicle.
17 Newton’s Three Laws1. Objects in motion stay in motion unless an external force is applied (law of inertia)2. Force is equal to mass times acceleration (F=ma)3. Every action has an equal and opposite reaction.
18 Gravity Physical bodies attract each other Gravity on Earth is why things fall and have weightFalling objects all accelerate at the same rateAcceleration due to gravity is about 9.8 m/s2
19 Photo: Richmond Times-Dispatch WorkWhen a force does work, it acts on a body and moves (or displaces) itWork is measured in joulesWork equals force times displacement (W=fd)Photo: Richmond Times-Dispatch
21 Structure of matter Atom is the smallest unit of matter Atoms consist of a nucleus with protons and neutrons surrounded by a field of electronsAtoms group together to form moleculesimage: Fastfission
22 States of Matter Solid, liquid, gas and plasma States change when temperature changesAs states of matter change molecules get further apart and move around more easily
23 Density The amount of mass a substance has per its volume (D=m/V) In liquid or gas form, less dense substances float on more dense substances
24 Chemical EquationsShow a chemical reaction using chemical abbreviations2HCl + 2Na -> 2NaCl + H22 atoms hydrochloric acid (HCl) react with 2 atoms sodium (Na) to create 2 atoms salt (NaCl) and Hydrogen (H2)Nothing is wasted- everything on one side is on the otherSometimes energy is given off
25 SolubilityAbility for a substance (the solute) to dissolve into another substance (the solvent)Once dissolved, a solution is formedIncreasing heat of the solvent allows more of the solute to dissolve- like dissolving sugar in tea