Law of Conservation of Energy & Pie Charts Practice. ENERGY- Something that can change the condition of your system; -is measured in Joules(J)

Transcription

1 Law of Conservation of Energy & Pie Charts Practice ENERGY- Something that can change the condition of your system; -is measured in Joules(J)

2 Law of Conservation of Energy First proposed by Mayer & Joule in 1842 This is a law that governs all natural phenomena of energy There is no known exception to this law If we calculate the energy in a system and then allow it to undergo changes, when we calculate again. IT IS ALWAYS THE SAME AMOUNT!!

3 LAW OF CONSERVATION OF ENERGY Energy cannot be created or destroyed. It may be changed from one form to another but the total amount of energy never changes. This means that when we use energy, it doesn t disappear and can t be lost. (It could be changed into an energy type that we don t want though.

4 QUICK WRITE! TOPIC: energy & the law of conservation of energy

5 Feynman Analogy The following is a modern adaptation of a famous lecture given by Richard P. Feynman about the Law of Conservation of Energy. Richard Phillips Feynman (pronounced /ˈfaɪnmən/, May 11, 1918 February 15, 1988) was an American physicist known for his work in quantum mechanics, the theory of quantum electrodynamics and the physics of the superfluidity of supercooled liquid helium, as well as in particle physics. For his contributions to the development of quantum electrodynamics, Feynman, jointly with Julian Schwinger and Sin-Itiro Tomonaga, received the Nobel Prize in Physics in During his lifetime, Feynman became one of the best-known scientists in the world. He assisted in the development of the atomic bomb and was a member of the panel that investigated the Space Shuttle Challenger disaster. In addition to his work in theoretical physics, Feynman has been credited with pioneering the field of quantum computing, [2] and introducing the concept of nanotechnology. [3] He held the Richard Chace Tolman professorship in theoretical physics at the California Institute of Technology.

6 Analogy Imagine Stewie has some blocks which are absolutely indestructible, and cannot be divided into pieces. Each block is the same as the other. He has 100 of these blocks.

7 In our analogy, what does each block represent? A. Toys B. Energy C. The System D. An Energy Transformation

8 Each day, Stewie s mom arranges all 100 blocks in his bedroom.

9 In our analogy, what does Stewie s bedroom represent? A. A bedroom B. Energy C. System D. Energy Transformations

10 System: This is the area we want to look at Systems can be OPEN or CLOSED. Stewie s bedroom is the closed system we are interested in. Because it s a CLOSED SYSTEM, energy can t go out of it and more energy can t be added to it. We look at how energy may move around within that system.

11 If energy can exit your system or be added by something outside the system, then your system is OPEN.

12 QUICK WRITE! TOPIC: energy & Stewie s room

13 One day, Lois came in at the end of the day and counted only 99 blocks! She searched the room. Sure enough, Stewie had hidden one of his blocks under the rug!! Now there is 100 blocks!!!

14 In our analogy, what does the block under the rug represent? A. Toys B. Lost Energy C. Kinetic Energy (moving energy) D. Potential Energy(stored energy)

15 If the system is closed, then A. The total energy will break apart in the system B. The total energy will decrease because energy can leave C. The total energy will remain the same in the system D. The total energy increases because it is transformed

16 Pie Charts can be used to show the amount of energy present before, during and at the end of an energy transformation.

17 Define your System first: Remember to make it big! We will say this is a CLOSED SYSTEM that doesn t allow any energy to leave or enter. SYSTEM: BALL & EARTH THINK ABOUT IT- What kinds of energy are in our system?

18 What type(s) of energy do we have during the ball drop? A. Kinetic B. Potential C. Kinetic and Potential D. No energy

19 How much PG energy do we have at the top of the drop? A. 25% (Joules) B. 50% (Joules) C. 75% (Joules) D. 100% (Joules)

20 How much potential gravitational energy do we have at the bottom of the ball drop? A. 0% (Joules) B. 50% (Joules) C. 25% (Joules) D. 100% (Joules)

21 What type and form of energy do we have at each point in the ball drop (assuming that it starts from rest)?

22 Where does all of the potential gravitational energy go? A. It goes into the floor B. It turns into kinetic energy C. It leaves the system D. It turns into potential energy

23 QUICK WRITE! TOPIC: energy & Pie Charts