1. TAKS objective 4 Energy, Forces, and Motion Middle School Science Science TAKS Need to Know 1

2. Energy The ability to do work or to cause change Science TAKS Need to Know2

3. Chemical Energy – Energy transformations Science TAKS Need to Know3 Chemical energy – when light energy from the sun is converted to the energy in the bonds of the sugar molecules formed in photosynthesis.

4. Chemical Energy Examples of chemical energy changing into heat energy: Lighting a match Burning a wood fire Science TAKS Need to Know4

5. Heat energy- Energy transformations Heat energy – energy is absorbed and temperature rises. Specific heat- the ability of a substance to absorb heat energy Science TAKS Need to Know5

6. Specifics of Specific Heat Specific heat capacity of water is larger than soil, so the rise of temperature is less for water, all other things being equal. But, there's another effect: Sun's energy penetrates farther into water than it does into earth, so the temperature rise per square meter of exposed surface is less for water. 6Science TAKS Need to Know Temperature is a measure of the average kinetic energy of the molecules in the object. ----------------------------------------- Will both fingers feel the same temperature when they're put in the warm water? Water Holds Thermal Energy at Lower Temperature

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8. Electrical energy- Energy transformations Science TAKS Need to Know8 Electrical energy- flow of electrons (a current) Other ways of generating electricity: Water flowing through a dam in a river to move turbines Wind generators that use the energy of moving wind & operate a generator Nuclear power plants convert atomic energy into heat. Heat boils water to form steam & then follows the same energy transformations as coal power plants

9. Many energy transformations… Science TAKS Need to Know9 Electrical to mechanical: Electricity used to spin the CD (Spinning CD has mechanical energy due to its position or motion) Electrical to sound: A laser converts the digital information on the CD into electrical energy and this energy goes to the headphones as a vibration- this transmits Sound! Chemical to electrical: Batteries store chemical compounds that react when they are used to power something. This produces a flow of electrons which is electricity!!

10. Sound energy- Energy transformations Science TAKS Need to Know10 Sound – consists of mechanical energy waves created by vibrations. Sound must travel through something (called “medium” or “media”) such as air, water, or a solid. The medium carries the energy of the wave from one place to another. Example: Air transmits the energy of the vibrating material in the headphones to your eardrums. A vacuum is a space that contains little or no matter. Sound can’t travel through a vacuum since there are no particles to squeeze together (compression) or spread apart (rarefaction)

11. Many times it takes a whole series of energy conversions to do a certain job. For example, just to get the energy to make a piece of toast, there are several energy conversions involved. Chemical energy stored in coal is released as heat and light energy when the coal is burned. The heat energy is used to produce steam and is changed into mechanical energy in a generator. The generator converts mechanical energy into electrical energy that travels through power lines into your home. When you use your toaster, that electrical energy is again changed into heat energy. Have you ever touched a light bulb when it was on? Or tried to change it when it burnt out after being on? What you have discovered is the conversion process of energy- When you turn on a light, not all of the electricity is converted to light energy. Some of the energy is converted to heat. Remember, energy is never lost- it’s only converted from one form to another. This is the law of conservation of energy Science TAKS Need to Know11

12. Science TAKS Need to Know12 Light waves do not need a medium to transmit energy! They can even travel through empty space.

13. A wave is a disturbance that transfers energy from one place to another. Science TAKS Need to Know13 Water waves are a form of a wave that transmits mechanical energy across the surface of water.

14. Science TAKS Need to Know14 Seismic waves are caused by earthquakes that transmit mechanical energy through the Earth’s layers.

15. Potential (PE) Science TAKS Need to Know15 Stored energy

16. Kinetic Energy (KE) Science TAKS Need to Know16 Energy due to motion of an object Speed & mass affect kinetic energy– Faster/heavier…more Kinetic Energy Did you know that the gas burned in a car engine is chemical energy being turned into Kinetic Energy? Rubber band flying through the air has kinetic energy

17. Before the yo-yo begins its fall it has stored energy due to its position. At the top it has its maximum potential energy. As it starts to fall the potential energy begins to be changed into kinetic energy. At the bottom its potential energy has been converted into kinetic energy so that it now has its maximum kinetic energy Science TAKS Need to Know17 A waterfall has both potential and kinetic energy. The water at the top of Bridal Veil Falls has stored potential energy. When the water begins to fall, its potential energy is changed into kinetic energy. This change in energy also happens at Niagara Falls where it is used to provide electricity from the transformation of mechanical and electromagnetic energy.

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19. Energy Transformations Potential energy A rock sitting at the top of a cliff Roller coaster car at the top peak of a hill A swimmer posed to dive off the end of a diving board NO MOTION !! Kinetic energy A bouncing ball A moving roller coaster A track star running A girl skiing MOTION is the key!!!! Science TAKS Need to Know19

20. Science TAKS Need to Know20 Forces may MOVE objects Forces may transfer energy between objects

21. A book resting on a desk illustrates balanced forces. However, a book dropped from a desk illustrates unbalanced forces. In this case, gravity has overcome the balance of forces. Science TAKS Need to Know21

22. You use force to move your body Science TAKS Need to Know22 When you bend your arm, your muscles contract, which applies force to your arm bones. Your arm responds to this force by moving. During breathing, muscles contract (use force) to move air in and out of the lungs. The heart contracts (uses force) to pump blood through the blood vessels, carrying oxygen to the muscles.

23. All living things use force to move Science TAKS Need to Know23 Emerging seedlings exert force on the surrounding soil. This force pushes the stem of the plant out of the ground. Plants exert force to open flower petals, curl & uncurl leaves & push roots through the soil. Force is used to move materials in & out of cells. Fish exert force to swim by pushing against the water.

24. Science TAKS Need to Know24 In order for a force to move something, it must be an unbalanced force. This means that a force is stronger in one direction than the forces in the opposite direction.

25. Science TAKS Need to Know25 Acceleration of an object moving in one direction is the speed (m/s) per unit of time (s), or change in speed divided by time. The unit for acceleration is m/s 2.

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27. Data can be displayed & interpreted in many ways Science TAKS Need to Know27

28. Force & motion are related Science TAKS Need to Know28

29. What’s the advantage to knowing how much force we use to do something??? Science TAKS Need to Know29

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33. A lever is a bar that rests on a support called a fulcrum which lifts or moves loads. Science TAKS Need to Know33

34. Types of levers Science TAKS Need to Know34

35. Science TAKS Need to Know35 A pulley is a simple machine that uses grooved wheels and a rope to raise, lower or move a load. When a rope passes over a wheel, it changes the direction of effort (pull) needed to move the load. This pulley has 1 wheel, so it changes the direction of pull 1 time. The input force is the same as the weight using the pulley.

36. Wedge Science TAKS Need to Know36 A wedge is an object with at least one slanting side ending in a sharp edge, which cuts material apart.

37. An inclined plane is a ramp used to reduce the effort needed to raise or lower an object over a vertical height. It is easier to climb stairs to get to a second floor than to climb straight up a rope. It is easier to walk up a long, gentle hill than to climb up a short, steep hill. Examples of inclined planes: Loading ramp; Stairs or wheelchair ramp Mountain road; Threaded screw. The ancient Egyptians used inclined planes, or ramps, to move huge blocks of stone to build the pyramids. Science TAKS Need to Know37

38. A screw is an inclined plane wrapped around a pole Science TAKS Need to Know38

39. Wheel & axle Science TAKS Need to Know39 A wheel with a rod, called an axle, through its center lifts or moves loads.