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Science GHSGT Review

Science GHSGT Review. Physical Science. What is Physical Science?. Study of matter and energy Study of the physical world On GHSGT, physics and chemistry. Speed and Velocity. Speed = distance divided by time s = d/t Units of speed = m/s Velocity = speed in a given direction Example:

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Science GHSGT Review

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  1. Science GHSGT Review Physical Science

  2. What is Physical Science? • Study of matter and energy • Study of the physical world • On GHSGT, physics and chemistry

  3. Speed and Velocity • Speed = distance divided by time s = d/t • Units of speed = m/s • Velocity = speed in a given direction • Example: • 55 mph = speed • 55 mph north = velocity

  4. Distance versus Time Graph • AKA position versus time graph • Straight line represents constant (uniform) speed

  5. Acceleration • Acceleration = rate at which velocity changes • Involves a change in speed OR direction a = (vf – vi )/ t • Units of acceleration = m/s2 • Example: 0 to 60 mph in 5 seconds • For acceleration to occur a net (unbalanced) force must be applied

  6. Distance versus Time Graph Revisited • Non-linear graph represents acceleration • Parabola = constant acceleration

  7. Forces • Force = a push or a pull • Net Force = sum of all forces acting on an object • Free-body diagram shows all forces with vector arrows • Direction of force = direction of acceleration • Friction is a force that always opposes motion

  8. Determining the Net Force

  9. Newton’s 1st Law of Motion • An object at rest will remain at rest and an object in constant motion will remain in constant motion unless acted on by an unbalanced force. • Reason for seatbelts

  10. Newton’s 2nd Law of Motion • Force = mass x acceleration F = ma

  11. Newton’s 3rd Law of Motion • For every action, there is an equal but opposite reaction • Examples: • Punch a wall, it punches back • Rocket propulsion

  12. Gravity • Gravity = attractive force between two objects that have mass • Depends on mass and distance

  13. Effects of Mass and Distance on Gravity

  14. Momentum • Momentum is mass in motion p = mv • To change an object’s momentum a force must be applied • Conservation of momentum states that momentum before a collision equals momentum after

  15. Energy and Work • The ability to do work • Work = transfer of energy by applying a force to move an object W = Fd where force and distance are in same direction • Both work and energy are measured in Joules

  16. Examples of Work and No Work • Hammer applies a force to move the nail in the same direction = WORK • Waiter applies a force upward while the tray moves forward = NO WORK

  17. Types of Mechanical Energy • Kinetic = energy of motion • Potential = stored energy due to position

  18. Conservation of Energy

  19. Conservation of Energy

  20. Conversion of Energy • Motor = converts electrical energy into mechanical energy • Motors make fans Move which is Mechanical • Generator = converts mechanical energy into electrical energy • Georgia Power use a Generator to provide electricity

  21. Power • Power = rate at which work is done P = W/t • Measure in Watts • More work, less time = More Power • Less Work, Long time = Less Power

  22. Heat Energy • Heat can be transferred through: • Conduction = when objects touch • Convection = when matter moves • Radiation = in the form of waves • Conductors = easily transmit energy • Example: metals • Insulators = do not easily transmit energy • Example: gases such as air

  23. Light • Light is a form of electromagnetic radiation (EM) • EM spectrum shows the forms of radiation in order of increasing frequency and decreasing wavelength

  24. Color of Light • We see different colors depending on the frequency of light emitted or reflected • This is the reason blue flames are hotter than yellow. Blue has a higher frequency so more energy.

  25. Refraction of Light • Light waves travel faster in air than in water and slower in glass than water. • More dense = slower light • When light enters a different medium, speed changes and it bends. • Bending of light due to change in speed = REFRACTION

  26. Electricity • Electrons carry a negative charge. • Lost electrons = positive charge • Gained electrons = negative charge • REMEMBER: • Like charges repel • Opposites attract • An object can be charged through: • Friction (rubbing two objects together) • Conduction (touching a charged object to an uncharged object) • Induction (holding a charged object near an uncharged object)

  27. Electrical Circuits SERIES • Current flows in a closed circuit • Ohm’s Law • V = IR • Two types of circuits: • Series (single path) • Parallel (poly paths) PARALLEL

  28. Electromagnet • One can make an electromagnet with a nail, battery, and wire • When current flows through the coiled wire, the nail becomes magnetized.

  29. Electromagnetic Induction • Occurs when a current is produced by moving a conducting wire through a magnetic field

  30. Fundamental Parts of the Atom • Atoms are made of: • Protons (+) • Neutrons (neutral) • Electrons (-) • Most of the mass is in the nucleus (protons & neutrons) • Atomic number = number of protons • Silver has 47 protons • Atomic mass = number of protons + neutrons • Silver has 61 neutrons

  31. Periodic Table • Left of zig-zag line = metals • Right of zig-zag line = non-metals • Along the line = metalloids • Groups/Families = columns; go up and down • Group number indicates # of valence electrons • Rows/Periods = side to side • Period number indicates # of electron shells/energy levels

  32. Groups to KNOW • Group 1 = alkali metals (so reactive never found uncombined in nature) • Group 2 = alkaline earth metals (less reactive than alkali but more reactive than most metals) • Group 7 (sometimes 17) = halogens (very reactive non-metals) • Group 8 (sometimes 18) = nobel gases (non-reactive)

  33. Acids and Bases • pH determines how acidic or basic a solution is • pH 1-6 = acidic • Acids dissolve to release hydrogen atoms • Acid of pH 1 is much stronger than acid of pH 7 • Examples: HCl strong, Citric acid weak • pH 7 = neutral • De-ionized water • pH 8-14 = basic • Bases dissolve to release hydroxide ion (OH-) • Base of pH 8 is much weaker than base of pH 14

  34. Physical versus Chemical Changes • Physical changes are when no new substances are formed (i.e. phase changes such as melting, freezing, boiling, condensation, evaporation, sublimation) • Chemical changes occur when new substances are formed (i.e. rusting, foaming, burning) • Whether physical change or chemical change, MASS IS ALWAYS CONSERVED

  35. Phase Change Diagram

  36. Radioactive Decay ALPHA DECAY • Alpha and beta decay result in transformed atom • Gamma decay results in same atom with release of energy BETA DECAY GAMMA DECAY

  37. Half-Life • Half-life is the decay of some unstable isotopes at a consistent rate that can be calculated. • For example: Isotope X has a half life of 100 years, if I have 50 g of Isotope X, how much will remain after 100 years? After 200 years?

  38. Good luck! You can do it!!!

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