1. SCIENCE PSSA REVIEW TOPICS and KEY TERMS

2. Physical Sciences Matter- anything that has mass and volume Phase change- change form one state to another freezing = to a solid boiling = to a gas Density= Mass/volume * Two objects with same mass can have different volumes EXAMPLE: One kg feathers has different volume than 1KG iron

3. Solubility= the ability of one substance to dissolve in another Chemical property- observation or measurement by changing one substance into another EX burn wood Chemical properties = acidic or basic acid  turns blue litmus red and tastes sour (lemons) base  turns red litmus paper blue and tastes bitter (soap) Indicator  substance that changes color when it comes in contact with acid or base **Neutral = neither acid or base

4. MATTER Element- simplest substance, cannot be broken down simpler Atom- smallest unit of an element that has all chemical properties of that element Compound- two or more elements chemically combined Molecule- two or more atoms bonded by shared electrons

5. Mixtures- combination of substance that maintain individual identities EX salad Filtration- separates a mixture using difference in state or particle size Evaporation- liquid to gas Distillation- separating parts of a liquid mixture based on boiling points of the parts

6. Chemical Changes Chemical reactions- when a substance changes into another Reactants- put into equations Products- results/produced Reactants Products 6CO 2 + 6H 2 O + sun------> C 6 H 12 O 6 + 6O 2

7. Forms and Energy Sources Energy- ability to do work Potential energy (PE)- energy stored/capable Kinetic Energy (KE)- moving energy Mechanical Energy (ME)  PE + KE

8. (Forms of energy continued) Heat – energy that moves from warmer to cooler objects Chemical energy- energy stored in bonds Nuclear energy- energy stored in nucleus of atom ** Chemical and nuclear and both forms of potential energy

9. (Forms of energy continued) Electrical energy- energy of moving electrons Light energy- energy in electromagnetic waves Sound energy- travels in waves and is produced by vibrating objects **Energy sources are renewable or nonrenewable Renewable- cannot be used up EX. Water, wind Nonrenewable- can be used up EX. Sun, fossil fuels (coal, oil, gas)

10. Energy Transfer and Conversion *Law of Conservation of Energy: energy cannot be created or destroyed Conduction- energy moves within an object or between objects that are touching Convection- energy is carried from one place to another Radiation- energy is transferred through waves ** Diagram next page

12. Energy Conversion Changing one form into another EX. Kinetic  potential = pedaling a bike uphill Chemical  light = flashlight Electrical  sound = telephone Light  chemical = photosynthesis

13. ENERGY RESOURCES Fossil fuels- nonrenewable resources: coal, oil, gas ** Burning fossil fuels pollutes and causes Global warming (increase in average global temperature) Nuclear fission (nonrenewable)- the nucleus of an atom splits, releasing large amounts of energy

14. RENEWABLE ENERGY SOURCES Biomass - material from an organism that is used as energy source (plants, feces..) Hydroelectric- water falls on turbine Geothermal- heat used from within Earth's crust *Generator-machine that converts motion into electricity *Turbine- machine that turns because of moving energy from moving fluids such as air, water, steam

15. Force, Motion, Newton’s Laws Force- push or pull that can change motion Friction- force that resists motion Net force- total size and direction of forces on the object ** Matter attracts other matter with the force of gravity

16. Balanced and Unbalanced Forces

17. Net Force EXAMPLES:

18. Newton’s Laws of Motion FIRST LAW: An object at rest will remain at rest unless acted on by an unbalanced force. This law is often called "the law of inertia". Simply: there is a natural tendency of objects to keep on doing what they're doing.

19. Second Law: Acceleration is produced when a force acts on a mass. The greater the mass (of the object being accelerated) the greater the amount of force needed (to accelerate the object). Simply: heavier objects require more force to move the same distance as lighter objects.

20. Third Law: For every action there is an equal and opposite re-action. Simply: whenever an object pushes another object it gets pushed back in the opposite direction equally hard.

21. SIMPLE MACHINES: makes work easier by changing the size or direction of a force applies to them Description and examples: wheel and axle (windmill, fan) inclined plane (roller coaster, stairs) Wedge (sledge hammer, chisels) Screw (door lock, drill) Pulley (flag pole, window blinds) Lever (seesaw, rake)

22. TYPES OF LEVERS First-class levers have the fulcrum placed between the load and the effort, as in the seesaw, crowbar, and balance scale. If the two arms of the lever are of equal length, as with the balance scale, the effort must be equal to the load. If the effort arm is longer than the load arm, as in the crowbar, the effort travels farther than the load and is less than the load.

23. Second-class levers have the load between the effort and the fulcrum. EX. Wheelbarrow - The wheel’s axle is the fulcrum, the handles take the effort, and the load is placed between them.

24. Third-class levers : effort placed between the load and the fulcrum. A hammer acts as a third-class lever when it is used to drive in a nail: the fulcrum is the wrist, the effort is applied through the hand, and the load is the resistance of the wood. Another example of a third-class lever is the human forearm: the fulcrum is the elbow, the effort is applied by the biceps muscle, and the load is in the hand.

25. Mechanical advantage: MA = output force/input force MA = input distance/ output distance Example: A construction worker uses a board and log as a lever to lift a heavy rock. If the input arm is 3 meters long and the output arm is 0.75 meters long, what is the mechanical advantage of the lever? MA= 3/.75 = 4