1 / 30

Physical Science Review for the GCRCT

Physical Science Review for the GCRCT. 8 th Grade Physical Science. The Scientific Method. Step 1: Ask a Question Step 2: Form a hypothesis (based on observations) Step 3: Test the hypothesis (experiment) Step 4: Analyze the results (data from exp.) Step 5: Draw conclusions

posy
Télécharger la présentation

Physical Science Review for the GCRCT

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Physical Science Reviewfor the GCRCT 8th Grade Physical Science

  2. The Scientific Method • Step 1: Ask a Question • Step 2: Form a hypothesis(based on observations) • Step 3: Test the hypothesis (experiment) • Step 4: Analyze the results (data from exp.) • Step 5: Draw conclusions • Step 6: Communicate results

  3. The Scientific Method • Theory – An explanation based on observations, hypothesis and experiments. Ex: Big Bang. • Law – Summary of many observations and experimental results telling how things work. Ex: All of Newton’s Laws • Models – a representation of an object or system.

  4. The Basics of Physical Science • All sciences are based in physical science: • Geology – studies Earth and Earth activities • Biology – studies how living things work • Botany – studies plant life • Ecology – studies environmental issues

  5. International System of Units (SI) • Based on the number 10 • Prefixes: milli (1/1000th), centi (1/100th), deci (1/10th), main unit, kilo (1000) • Length = meters • Mass (not weight) = grams • Volume = liters (liquids) cm3 (solids) • Weight depends onmassandgravity measured in Newtons

  6. Measurements • Area = Amount of surface: length x width (e.x. cm2) • Volume = How much an object can hold: length x width x height (e.x. cm3) • Density = Amount of matter in a given space: mass volume ex: g/ml Force = a push or pull, measured in Newtons (as isweight)

  7. Measurement Tools • Thermometer - measures temperature • Balances – measures mass (in grams) • Ruler – measures length (in meters) • Graduated cylinder – measures volume

  8. Physical Properties/Changes • Physical properties include changing states (solid/liquid/gas/plasma), measurements such as length, height, density- keeps same identity. Changing any of these causes a physical change. • Chemical properties change the identity a substance through burning (applying heat) or creating a chemical reaction (ex: rusting). When this occurs, you have a chemical change that makes a new substance.

  9. Atoms • Atom – smallest part of an element. • Atoms are made of protons (+),neutrons and electrons (-), which are outside the nucleus. • Electrons are in an electron cloud. They can move from level to level, or they can bond with other atoms. • Isotopes – are atoms that have the same # of protons, but different # of neutrons (ex: C 14)

  10. Atoms and Electron Bonding • Ions – Charged atoms when valence electrons transfer from one atom to another (ionic bonding). • Covalent bonding – Electrons don’t transfer, but the atoms combine by sharing valence electrons.

  11. The Periodic Table • Atomic number - # of protons – how the Periodic Table is arranged. • Mass number - # of protons and neutrons • amu – atomic mass units (measurement) • Elements – cannot be broken down into simpler substances.

  12. The Periodic Table • Arranged by family/group (same physical and chemical properties), and rows/periods (has same repeating patterns). Classified by metals, metalloids and non-metals. • Largest group is metals. Good conductors of electricity/heat, malleable, ductile, can react with water.

  13. Mixtures and Compounds • A mixture is when 2 or more substances are mixed, but there is no chemical bonding (they can be separated). Ex: cake mix. • A compound is a substance made up of 2 different elements that are chemically bonded. Ex: NaCl, H20 The subscript number is the number of atoms in a compound. H20 means there are 2 atoms of hydrogen.

  14. Solutions • Solutions are when one substance is dissolved into another substance (salt water) • The solubility of most solids increases as temperature increases (ex: higher temps. melt butter). • Water is the universal solvent.

  15. Gravity, Mass and Weight • Gravity: A force of attraction between 2 objects, depending on their mass and distance from each other. • Weight is dependent upon gravity. • Mass does not change when gravity changes, only weight.

  16. Friction • Friction is a force that opposes an object’s motion. • Sliding – moving items across a surface • Rolling – use of wheels • Fluid – any gas or liquid (water, air, etc.) Air resistance is an example. • Static – built up electric charges • Viscosity – A liquid’s resistance to flow. The more dense, the greater the viscosity.

  17. Force • Can cause an object to speed up, slow down, or change direction, is a push/pull, and is measured in newtons. • You have to exert a greater force to overcome gravity (inertia) or friction. • Net force is the total extra force needed to move an object. (10N west vs. 5 N east = 5 N west) • Gravity depends on mass and distance. • Greater mass = greater gravity • Greater distance = less gravity

  18. Speed, Velocity & Acceleration • Frame of reference is what you are using to compare the movement of an object. • Speed is distance over time (ex. km/hr) • Constant speed graphs – show no change. • Velocity is speed plus direction (ex. km/hr south) Acceleration – change in speed or direction

  19. States of Matter • Freezing/boiling points are physical properties. • Solids – particles can’t overcome gravity to move • Liquids – particles can move, but not break away from each other • Gas – particles can move past each other, creating areas of empty space. Particles move faster when temperature increases.

  20. Pressure and Temperature • Pressureis the amount of force over a given area. • Boyle’s Law: when volume changes, pressure changes (ex: blowing up a balloon) • Charles’s Law: When temperature changes, volume and pressure changes.

  21. Fluid Pressure • Like gravity, atmospheric pressure decreases as you move upwards (less on a mountain) • Fluids (gases/liquids) travel to areas of leastpressure (ex: straws, your ears on airplane). • Fluids flow equally in all directions.

  22. Fluids and Density • When fluids have different densities, they separate (less dense on top). • Denser objects can float if they have a change in shape (ex: ship)

  23. Energy Transfers • Conduction – transfer of energy (electrical or thermal) by direct contact. (Ex: boiling water on stove – heating unit to pot to water) • Convection – Transfer of heat by the movement of the liquid or gas (boiling water) • Radiation – Transfer of heat through matter or space (ex: the Sun or other electromagnetic waves.)

  24. Energy Conversions • Energy is never lost or created, it just changes form (Laws of Conservation) • All energy transfers into some form of thermal (heat) energy (ex: light bulb) • Mechanical energy is energy of motion or position (ex: machines)

  25. Energy • Potential Energy– stored energy • Kinetic Energy – Energy in motion • Energy Resources: • Fossil Fuels and Nuclear Energy are nonrenewable. • Fossil Fuels are our greatest source of energy.

  26. Momentum • Newton’s 2nd Law: Greater the mass and velocity, the greater the momentum (ex: large truck vs small car) • Law of Conservation of Momentum: Momentum is not lost or gained (same after an accident as before the accident).

  27. Waves • Amplitude – the height of a wave from area of rest to top of crest. Shows the amount of energy of wave. • Wavelength – distance from crest to crest or trough to trough. The number of wavelengths passing a point during a given time is frequency.

  28. Wave Types Transverse Waves • Do not need a medium. • Examples are all electromagnetic waves. Longitudinal Waves Sometimes called mechanical waves • Resemble a “slinky” – series of compressions and rarefactions • Sound waves are longitudinal waves

  29. Sound • Travels approx. 350 m/s. • Can travel faster through solids. • Amplitude = energy (how loud) • Frequency = how fast wave is traveling • When you or sound approach, sound increases. As you move away, it decreases. This is the Doppler effect (change in frequency).

  30. Light • Light travels in a transverse wave (300 million m/sec in a vacuum) • Divided by wavelengths: Radio to Gamma Color wavelengths: long = red, short = violet • All wavelengths together make white, lack of all light reflected is black. • The wavelengths reflected back are the colors you see.

More Related