GED Physical Science

Heat Heat is the flow of energy from a cold object to a warmer one. Heat can be transferred by convection, conduction, or radiation

Transfer of heat Conduction- Transfer of heat through direct contact Convection- Heat transfer through hot particles rising and cool particles falling Radiation- Hot particles moving away from a reaction (like a fire).

Transfer of Heat

Heat in Reactions Endothermic reactions absorb heat from surroundings. Examples: melting ice, evaporating liquid Exothermic reactions give off heat. Examples: fire/combustion, condensation of liquids

Potential and Kinetic Energy Kinetic energy is energy of motion When an object is in a high place it has potential energy because of gravity When it gains speed as it falls it converts potential energy to kinetic energy. Photo: University of Richmond

Chemical Energy Chemical energy is potential energy that could be converted to other types or energy by chemical reaction Chemical energy of food can be converted to kinetic energy (movement) by cells in the body Combustible materials contain chemical energy that is given off when they burn

Photo: TheDailyNathan Mechanical Energy Sum of potential and kinetic energy Remains constant: potential energy is converted to kinetic energy and back. Photo: TheDailyNathan

Sources of Energy: The Sun Heat energy radiates from sun and is absorbed in solar panels Method of energy production that reduces pollution Sustainable, but reliant on sunlight

Sources of Energy: Fossil Fuels Oil, Coal and Natural Gas are mined or drilled and burnt, producing energy Fossil Fuels may not be sustainable because there is a finite amount Fossil fuels produce pollution

Sources of Energy: Nuclear Splitting an atom (nuclear fission) gives off heat in a reaction and the energy is harnessed Sustainable, but does produce some nuclear waste Threat of accidents (Chernobyl/Fukushima)

Waves Waves transfer energy Electromagnetic waves transfer energy by vibration of electric and magnetic fields Water waves transfer energy by moving particles of water Sound waves are movement of particles transmitting sound

Parts of a Wave Wavelength: Distance between waves Amplitude: Height of waves Frequency: How many waves occur in a time frame Higher wavelength means lower frequency.

Electromagnetic Spectrum image: Simon Baier

Forces in Physics Speed: Distance traveled in a period of time (magnitude of velocity) Velocity: Speed moved in a direction Acceleration: rate of increase of velocity Momentum: mass of an object times the velocity. A large object has more momentum than a small one moving at the same velocity

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.

Newton’s Three Laws 1. 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.

Gravity Physical bodies attract each other Gravity on Earth is why things fall and have weight Falling objects all accelerate at the same rate Acceleration due to gravity is about 9.8 m/s2

Photo: Richmond Times-Dispatch Work When a force does work, it acts on a body and moves (or displaces) it Work is measured in joules Work equals force times displacement (W=fd) Photo: Richmond Times-Dispatch

Structure of matter Atom is the smallest unit of matter Atoms consist of a nucleus with protons and neutrons surrounded by a field of electrons Atoms group together to form molecules image: Fastfission

States of Matter Solid, liquid, gas and plasma States change when temperature changes As states of matter change molecules get further apart and move around more easily

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

Chemical Equations Show a chemical reaction using chemical abbreviations 2HCl + 2Na -> 2NaCl + H2 2 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 other Sometimes energy is given off

Solubility Ability for a substance (the solute) to dissolve into another substance (the solvent) Once dissolved, a solution is formed Increasing heat of the solvent allows more of the solute to dissolve- like dissolving sugar in tea