Do Now 10/23 Do not pick up a pink sheet today. Just find your seat, get out your journal and a pencil. You will have 3 minutes to ask questions before the test.

Do Now 10/24 1. What is the definition of Energy? 2. List as many forms of energy as you can.

Do Now 10/25 The bar graph shows the energy of the skater. Where could she be on the track? Explain your thoughts A B C D E Sim demonstration: Open the simulation and explore the skateboarder’s behavior with no friction, but without displaying the bar graph during the demonstration. Correct answer: D Representative results from pre-general chemistry: 62-69% correct (next most popular was C at 20-30%) Follow-up discussion: Ask students how they determined their answer, and discuss conservation of mass. Ask students how they determined their answer, and discuss conservation of mass. It may also be worthwhile discussing points C vs. D and how the change in potential energy is related to height (depending on how many students vote C vs. D).

Do Now 10/26 A. Luis say that since both A and B are at the bottom of the hill, that their Kinetic Energies will be equal because you have the highest amount of kinetic energy at the bottom of the hill. B. James says that A and B will NOT be equal because there is a different amount of potential energy at point A then at point B. C. Marcy says that A and B will not have equal kinetic energies. Because you did not start with the same total energy. Who is correct, explain. B A

Friction friction simulation

At some point, the skater had the energy shown in this graph. 1. Describe his speed at that point. (choose one) DO NOW 10/30 He is at his maximum speed He is stopped He is going his average speed He is going slow He is going fast Sim demonstration: Open the simulation and explore the skateboarder’s behavior with no friction, but without displaying the bar graph during the demonstration. Correct answers: A Representative results from pre-general chemistry: 53-63% correct (next most popular was C between 25-30%) 2. Is this a system with or without friction? How do you know?

Do Now 10/31 Take a look at your progress report. Please highlight anything you have that is missing or a zero. Also take a look at the formative % and summative % . Is there a correlation between the two?

Do Now 11/1 What is the total energy of the system? PE = 10J KE= 5 J THE = 3 J 2. Where on the ramp would the skater be if this is the total energy? Draw it.

Mechanical energy - total potential + kinetic energy of the system Energy – Trade-off with machines LT: To measure the amount of energy it takes to move an object and consider the trade-offs in using a machine Vocab: Mechanical energy - total potential + kinetic energy of the system Thermal Energy – energy in the form of heat Joules (J) – Unit of Energy Newtons (N)- unit for Force

Dominos Rube Goldberg Honda commercial Who is Rube Goldberg

Energy – Trade-off with machines Read 434-435 and write down 5 key points ( or take Cornell notes) 5 Key Points When a force is exerted energy is transferred Mechanical devices decrease the amount of force needed to do work Mechanical devices DO NOT SAVE energy – they reduce force Friction converts expended energy to heat ( thermal energy) Efficiency is a measure of how much usable energy is lost when using a machine.

Energy – Trade-off with machines Work = the amount of energy it takes to move an object over a distance. It is the amount of energy expended. Weight is overcoming the force of gravity. When you lift something you are transferring potential energy to the system. ( You are doing work on the object) Let’s Practice Energy expended ( J) = force (N) x distance it moved ( m) Energy Transferred ( J) = weight of object (N) x distance lifted (m) Ex: You use 3 units of force ( N) to move a chair 3 m. How much energy did you expend? E = 3x3 E= 9 J

Energy – Trade-off with machines Ex: You pick up 10 N of books ( 2.224lbs) 2 meters E = 10N x 2m E = 20 J

Do Now 11/2 Work ( energy) = force x distance The energy used to move a 5 N object was 50 J . How far was the object moved? An object is moved 70cm with 5N of force. How much work was done on the object?

Energy – Trade-off with machines Data Collection: Question – Do machines help us do less work? In your journal complete the procedure on page 436-437 Set up a table like this: Data Table Action distance lifted /moved (m) force (N) energy transferred J/energy expended( Work) Lifting Object Using Ramp