Sensing and Using Energy

1. Sensing and Using Energy

2. Heat Energy • Heat energy has to do with the internal motion of particles of matter • The greater the motion of the particles the more heat that is involved.

3. Solar Energy • Solar Energy comes from the sun. • Solar Energy is also referred to as Light Energy. • It is the reactant energy in photosynthesis.

4. Mechanical Energy • Mechanical Energy is the energy of motion. • In our bodies during respiration we convert chemical energy which is stored in foods into mechanical energy so we can move.

5. Chemical Energy • Chemical Energy is stored in foods. • Chemical Energy is also released when a chemical reaction takes place. • For example when a firework explodes you have chemical energy being converted into light energy.

6. Electrical Energy • Is the movement of electrical charges. • Items that needs plugged in like a lamp convert electrical energy into light energy. • Batteries in a small car can convert electrical energy into mechanical energy.

7. Potential and Kinetic Energy • Energy that is stored and held in readiness is called Potential Energy. This type of energy has the potential to do work. • The energy of motion is called Kinetic Energy. The word kinetic comes from the Greek word “kinetos” which means “moving.”

8. Potential and Kinetic Energy • Potential Energy and Kinetic Energy are cyclically. They are types of mechanical energy. • Think about it when you stretch a rubber band, you give it elastic potential energy. If you let it go, the rubber band flies across the room. • When the rubber band is moving, it has kinetic energy. The potential energy of the stretched rubber band is converted to the kinetic energy of the moving rubber band

9. Energy Conversion in a Ball Bouncing • Think about when you bounce a ball. • When does it have the most kinetic energy? • When does it have the most potential energy? • When would it have equal amounts of potential and kinetic energy?

10. Energy Conversion in a Pendulum • A continuous conversion between kinetic and potential energy takes place in a pendulum. • As the pendulum swings outward and slows down it has more potential energy. • As the pendulum goes back towards the middle it gains kinetic energy.

11. Pendulum Question • At which point on the pendulum’s swing is the kinetic energy the greatest? • At which point on the pendulum’s swing is the potential energy the greatest?

12. Energy Conversion in a Dam • As water flows through a dam it can be used to create electrical energy. • The electrical energy is formed from the water's stored gravitational potential energy. • Why do you think it is called GRAVITATIONAL POTENTIAL ENERGY?

13. Energy Conversion Examples • A change from one form of energy to another is known as energy conversion. • Energy is neither created nor destroyed but only changes form. • Most forms of energy can converted into other forms. • A toaster for example converts electrical energy into thermal energy.

14. Energy Conversion Examples • Your body converts chemical energy in the food you eat to the mechanical energy you need to move your muscles. • Chemical energy in food is also converted to the thermal energy your body uses to maintain it’s temperature. • This is known as cellular respiration.

15. Energy Conversion Examples • Often a series of energy conversions is needed to do a task. • Strike a match, for example, and the mechanical energy used to scratch the match is converted to thermal energy. • The thermal energy causes the match to release stored chemical energy, which is converted to thermal energy.

16. Energy Conversion Examples • Photosynthesis converts solar energy into chemical energy which can be stored by the plant as food.

17. Detecting Light Energy • In some animals, the organ used to detect light is the eye. Although most large animals (humans, fish, birds, reptiles) have similar eyes, not all eyes are the same. • Some eyes are very complex, while others are simple in their function. • With our human eyes, we can see a variety of colors, shades, and sharp details of shapes by collecting the light reflected off of objects. • Detecting Light Energy

18. Hiking in a Cave • So let’s say one weekend as a class we decide to go hiking. • During our hike we find a large cave with many caverns. • As we travel further into the cavern we decide to turn out our light and it is completely dark. • How long will it take for our eyes to get use to the darkness? • Our eyes would never get used to complete darkness.

19. Detecting Light Energy • Life as seen through the eyes of an insect would look very different. Insect eyes come in two varieties–simple and complex. • Simple insect eyes, called ocelli, detect little detail but can tell different shades of light and dark. • Compound eyes are more complex. These organs function similarly to many human eyes bundled together and working as one.

20. Detecting Light Energy • Some critters have eyes that swivel on short stalks which help them to see in all directions with out turning their heads. • Have you ever tried to swat a fly? They have compound eyes that help them see behind them. They see behind them but can't detect shapes very well. So next time when you sneak up on a fly, pretend to being doing something else.

21. Detecting Light Energy • Plants can also detect light. In fact, if they couldn’t, we could not exist, as we know it. • Special organs in plants, called chloroplasts, collect light energy and use it to convert carbon dioxide and water into sugar for us. • There are special photoreceptors in plants called cryptochromes and phytochromes. These receptors release hormones called auxins which break down part of the cell wall so that the plant is not as rigid so it can bend towards light.

22. Detecting Light Energy • 'Phototropism' is directional growth in which the direction of growth is determined by the direction of the light source. • In other words, it is the growth and response to a light stimulus.

23. Detecting Sound Energy • Even though we can feel many types of vibrations with our hands, feet or other body parts, we understand sounds by using our ears. • Human ears, and the ears of other large animals, are generally made of an air chamber covered by a thin piece of skin-like material (your eardrum). • Animals Detecting Sounds

24. Detecting Sound Energy • Insect ears, like human ears collect and transform sound vibrations. • But, insects ears are called tympanic organs. Any idea why they have this name? • It is because the membrane vibrates like a drum.

25. Detecting Sound Energy • Fish have what is called a lateral line system to help detect sound vibrations in water. This helps them detect when predators and other objects are near. • The lateral line looks like dashed or dotted lines on the sides and around the head of fish, reptiles and amphibian • This system also helps these animals sense movement of water past their bodies, and the temperature of the water.

26. Detecting Thermal Energy • Have you ever burned your hand on the stove? How does your brain actually know that your hand is getting warm? • We, like other animals, have certain nerve endings that are sensitive to heat. • These are often called thermoreceptors.

27. Detecting Thermal Energy • For some animals, such as some amphibians, fish, and reptiles, these receptors are part of the lateral line system. • Insects also have thermoreceptors located on all sorts of different body parts.

28. Devices that Detect Energy • A seismograph records the ground movements caused by seismic waves as they move through the Earth. • Electronic seismographs convert ground movements into a signal that can be recorded and printed.

29. Devices that Detect Energy • In some people the eyeball is slightly too long or too short, so the image on the retina is slightly out of focus. • Fortunately, wearing glasses or contact lenses can usually correct this type of vision problem. • By wearing these products it helps focus light properly on the eyes.

30. Devices that Detect Energy • Telescopes use lenses or mirrors to collect and focus light from distant objects. • The most common use of telescopes is to collect and use light from space. • This allows astronomers to see objects they could not see with their eyes alone.

31. Devices that Detect Energy • Hearing loss is generally due to injury, infection, or aging. • Some types of hearing loss can be helped with hearing aids. Hearing aids are amplifiers. • Some are so tiny that they can fit invisibly in the ear. Others are made specifically for a person’s hearing loss and amplify specific frequencies.

32. Energy Conversion Questions • A car toy that is powered by batteries would be an example of the conversion of chemical energy to: • A. Heat Energy • B. Mechanical Energy • C. Nuclear Energy • D. Sound Energy • Answer: B

33. Energy Conversion Questions • Which position has the least kinetic energy? • Position 1 and 3 • Which position has the most kinetic energy? • Position 2 and 4 • Which position has the least potential energy? • Position 2 and 4 • Which position has the most potential energy? • Position 1 and 3

34. Energy Conversion Question • What energy conversion takes place during cellular respiration? • 1. Heat Energy to Mechanical Energy • 2. Heat Energy to Chemical Energy • 3. Chemical Energy to Light Energy • 4. Chemical Energy to Mechanical Energy • Answer: 4

35. Energy Conversion Question • What energy conversion takes place in photosynthesis? • 1. Heat Energy to Chemical Energy • 2. Light Energy to Heat Energy • 3. Light Energy to Chemical Energy • 4. Mechanical Energy to Chemical Energy • Answer: 3

36. Energy Conversion Question • Identify the energy change that takes place as a candle burns. • 1. Mechanical to Electrical Energy • 2. Chemical to Heat Energy • 3. Mechanical to Heat Energy • 4. Chemical to Mechanical Energy • Answer: 2

37. Energy Conversion Question • Which of these is an example of chemical energy being converted to electrical energy? • A. 9 Volt Battery in a Smoke Alarm • B. Sunlight Used by Plants in Photosynthesis • C. A Windmill generating Electricity • D. A Blender Grinding up strawberries. • Answer: A

38. Energy Conversion Question • The burning of vaporized gas in the cylinder of an automobile engine pushes the pistons. This is an example of an energy conversion from chemical to: • A. Electrical Energy • B. Heat Energy • C. Mechanical Energy • D. Nuclear Energy • Answer: C

39. Energy Conversion Question • Which of these is an example of electrical energy being converted to mechanical energy? • A. Flashlight • B. Sunlight used by Photosynthesis • C. Lightning Striking the Ground • D. Fan • Answer: D

40. Energy Conversion Question • Identify the energy change that takes place in a food blender. • 1. Mechanical to Electrical Energy • 2. Electric to Mechanical Energy • 3. Electric to Heat Energy • 4. Chemical to Heat Energy • Answer: 2