Energy

1. Energy

2. I can differentiate between potential energy and kinetic energy

3. Potential energy- is energy that results from the position or shape of an object. • Brainpop: Potential Energy • Kinetic energy is the energy an object has due to its motion • Brainpop: kinetic energy http://studyjams.scholastic.com/studyjams/jams/science/matter/energy-and-matter.htm

6. Kinetic energy depends on both speed and its mass. • Ex-Suppose you are hit with a tennis ball that has been lightly tossed at you. It probably would not hurt much. What if you were hit with the same tennis ball traveling at a much greater speed? It would hurt! The faster an object moves, the more kinetic energy it has. • Ex- Suppose a tennis ball rolls across the ground and hits you in the foot. Compare this with getting hit in the foot with a bowling ball moving at the same speed as the tennis ball. The bowling ball is much more noticeable because it has more kinetic energy than a tennis ball. The bowling ball has more kinetic energy because it has a greater mass.

11. STOP........  • Now time for an experiment • And  • A quiz...

13. Types of Potential Energy • Potential energy related to an object’s height is called gravitational potential energy. • The gravitational potential energy of an object is equal to the work done to lift it to that height. • Gravitational potential energy = Weight × Height

14. Gravitational potential energy = Weight × Height • For example, suppose a book has a weight of 10 newtons (N). If the book is lifted 2 meters off the ground, the book has 10 newtons times 2 meters, or 20 joules, of gravitational potential energy.

16. Types of Potential Energy • Elastic potential energy is the energy associated with objects that can be compressed or stretched. • Interpret Diagrams Which trampoline has the greater amount of elastic potential energy?

17. Types of Potential energy • Electric Potential  is the capacity for doing work based on the object's electric charge

18. STOP........  • Now time for an experiment • And  • A quiz...

20. mechanical energy • The form of energy associated with the motion, position, or shape of an object is called mechanical energy. • An object’s mechanical energy is a combination of its potential energy and its kinetic energy. • For example, the basketball in Figure 1 has both potential energy and kinetic energy. The higher the basketball moves, the greater its potential energy. The faster the basketball moves, the greater its kinetic energy. You can find an object’s mechanical energy by adding together the object’s kinetic energy and potential energy.

21. Mechanical energy = Potential energy + Kinetic energy

22. Assess Your Understanding Explain Why do the particles of objects have both kinetic and potential energy?

24. Remember: Law of conservation of Mass: Matter can not be created or destroyed, it can change forms.

26. thermal energy • The particles that make up objects are constantly in motion. • They have kinetic energy. • They also have potential energy. • The total kinetic and potential energy of the particles in an object is called thermal energy

27. chemical Energy • Chemical energy is potential energy stored in chemical bonds. • Chemical bonds are what hold atoms together.  • When these bonds are broken, this stored energy is released.  • For example, bonds are broken in your cells and release energy for  your body to use.

28. Assess Your Understanding • Explain Why do the particles of objects have both kinetic and potential energy? • The energy you get from eating a peanut butter and jelly sandwich is in the form of __________________energy.

29. Falling Object- A transformation between potential and kinetic energy occurs in the ball in the picture • As the height of the ball decreases, it loses potential energy. At the same time, its kinetic energy increases because its speed increases. • Its potential energy is transformed into kinetic energy.

30. Pendulum • A continuous transformation between potential and kinetic energy occurs in a pendulum. • Label the type of energy the pendulum has at positions A, B, and C.

33. STOP........  • Now time for an experiment • And  • A quiz...

35. Temperature is a measure of the average kinetic energy of the particles in an object. • As an object heats up, its particles move faster. • There are three scales to measure temperature: Fahrenheit, Celsius, and Kelvin. • absolute zero is the lowest temperature possible.

37. Thermal Energy • Temperature is a measure of the average kinetic energy of the individual particles in an object. • it is not a measure of the total amount of energy in an object. • Thermal energy is the total energy of all the particles in an object. • It depends on the temperature of an object, the number of particles in it, and how those particles are arranged.

39. Heat is the transfer of thermal energy from a warmer object to a cooler object. • The warmer object will cool down, and the cooler object will warm up until they are the same temperature. When this happens, heat stops transferring. • Heat is measured in the units of energy—joules.

42. Heat is transferred from warmer areas to cooler areas by conduction, convection, and radiation.

43. Convection is a type of heat transfer that occurs only in fluids, such as water and air. • When air is heated, its particles speed up and move farther apart. This makes the heated air less dense. The heated air rises to float on top of the denser, cooler air. Cooler air flows into its place, heats up, and rises. Previously heated air cools down, sinks, and the cycle repeats. • This flow creates a circular motion known as a convection current. Convection currents in air cause wind and weather changes.

44. Radiation is the transfer of energy by electromagnetic waves. • Radiation is the only form of heat transfer that does not require matter. • Ex- You can feel the radiation from a fire without touching the flames. • Ex- The sun’s energy travels to Earth through 150 million kilometers of empty space.

45. Conduction transfers heat from one particle of matter to another within an object or between two objects. • Ex- The fast-moving particles in the floor of the oven collide with the slow-moving particles in the uncooked pizza. This causes the pizza’s particles to move faster, making the pizza hotter.

46. Heat transfer goes on all around you allthe time, even on the beach. List at least one example of each type of heat transfer.

47. Pick one of the following situations and write your responses on a blank sheet of paper. Please use at least one of the three types of heat transfer in each response. • On a hot summer day, should you close all of the blinds and curtains in your home or leave them open? Why? • Although you do not touch the flames, your chest feels warm while you are sitting in front of a fireplace. Why does your back still feel cold? • The outdoor temperature is 85°F, and your friend comes to school in a dark blue outfit. Was this a smart clothing choice for today? Why or why not? • Why is your house warmer on the top floor and colder in the basement?

49. Some materials conduct heat well, while other materials do not. • A material that conducts heat well is called a conductor. • Metals such as silver are good conductors. • Some materials are good conductors because of the particles they contain and how those particles are arranged. Ex- A good conductor, such as the tile floor, feels cold to the touch because heat easily transfers out of your skin and into the tile. However, heat also transfers out of conductors easily. A metal flagpole feels much hotter on a summer day than a wooden pole would in the same place because heat easily transfers out of the metal pole and into your hand.

50. Some materials conduct heat well, while other materials do not. • Insulators are materials that do not conduct heat well. • Ex- A wooden pole and your living room rug are good insulators. • Ex- Other good insulators include air and wool. For example, wool blankets slow the transfer of heat out of your body.