Science GHSGT Review

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

32. 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

33. 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)

34. 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

35. 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

36. Phase Change Diagram

37. 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

38. 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?

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