Energy Chains Can you think of how the energy flows through a car? What would you start with? What types of energy transformations are happening?

Energy Transfer and Transformation Thermal Energy Thermal Mechanical Electrical Chemical Kinetic Energy

Can you construct an Energy Chain for a person hitting a softball to the outfield?

Hitting a softball into the outfield Chemical E to pick up bat from food. Ball has PE in the air Ball throw in air transform from PE to KE Bat hits ball transfers KE to ball Ball increases KE Gravity pulls on ball Air resistance slows ball down 8. Ball hits ground (Friction) 9. Balls KE is transferred to dirt as it flies up.

Constructing Energy Diagrams

Predict what this car is doing? Using Font Size Predict what this car is doing? Coming to a stop! The KE is deceasing over time as it is being transformed in heat and PE energy.

A car stopping as a standard Bar Graph KE HE

Using Circle Graphs Circle graphs can be used to illustrate energy flow. Each form is a represented by a portion of the circle. Multiple circle graphs can illustrate how the amount of energy in each form changes over time.

What do you notice at interval 4? Circle Graph Examine what is happening in these circle graphs? What do you notice at interval 4?

ENERGY CHAINS Let’s look at some systems where energy transformation is taking place…(i.e. changing from one type of energy to another type of energy.) Ramps Cars Bungee jumper A Pendulum A Hydroelectric Power Plant

Energy Ramp Label sections A-E w/ the appropriate level of PE and KE (Assume NO friction) PE= Max A PE= High KE=Min B PE= Med KE= Low C Use the following terms Maximum High Medium Low Minimum PE= Low KE= Med D PE= Min KE= High E KE= Max

PENDULUM E A B D C At which point is the KE greatest? What is the velocity at that point? Point C 5.6 m/s

Pendulum Energy Transformation Draw this pendulum diagram on white board A. PE=KE? Points 2 and 4 B. PE greatest? Points 1 and 5 C. KE greatest? Point 3 only D. KE lowest? 1 and 5 E. PE lowest? 3 only

1. Statement: The farther above the ground an object, such as a book, is raised, the greater the object’s Gravitational Potential Energy (GPE). Circle the statement below which most closely matches your thinking and then explain your thinking. 1.Yes, everything has some potential energy. 2. Yes, but it only gets potential energy when it falls. Yes, because gravity is stronger the higher you go up. 3. Yes, one thing that determines the GPE is the distance between the object and the ground. 4. No, there is no force or motion happening. 5. No, it is not in contact with anything which could give it energy.

PE = m x g x h remember…(gravity = 9.8m/s2) POTENTIAL energy (PE) Potential Energy (PE) is the stored energy of an object resulting from the position of the object in a system. PE is measured by multiplying the mass of the object times the gravity and then times the height. PE = m x g x h remember…(gravity = 9.8m/s2) Units are Joules!!! (J) 1 Joule= 1kg x m2/s2

POTENTIAL energy (PE) Examples of objects with high PE: A stretched rubber band Any hanging object Any compressed object (like a spring) Any object that is high up

PE Power Triangle P m g h Plug PE = m*g*h into a Power Triangle Write the equations when you solve for m and h. P E m g h

It’s how we will solve ALL problems!!! DUFAS It’s how we will solve ALL problems!!!

DUFAS D is for DATA U is for UNITS F is for FORMULA A is for ARRANGE S is for SOLVE

How DUFAS works… All problems will be worth 5 points. You will get 1 point for every DUFAS step. So…correct answers are only worth 1 point!

D is for DATA: Step 1: Pull out all of the DATA for the problem and label the numbers.

D is for DATA: Example: A mountain biker rides down a 42m high mountain with 2500 J of GPE. What is the mass of the mountain biker? What’s the formula for GPE? GPE= mgh Here’s what we know… h = 42m GPE = 2500J Are we missing anything? Gravity 9.8 m/s2

U is for UNITS: Step 2: ALL numbers throughout the ENTIRE problem must have CORRECT UNITS!!! h = 42m GPE = 2500J gravity = m/s2

F is for FORMULA: GPE=mgh Step 3: You must write the equation for EVERY problem. GPE=mgh

A is for Arrange: Step 4: You must re-arrange the original FORMULA to solve for the data you are missing. Will the formula GPE=mgh work? NO

A is for Arrange: Example: A mountain biker rides down a 42m high mountain with 2500 J of GPE. What is the mass of the mountain biker? ARRANGE to solve for m!!! (USE the POWER TRIANGLE!!!)

POWER TRIANGLE If there is a fraction in the formula then the variable at the top of the fraction goes on top of the triangle. Solve for mass So for m= PE gh PE m g h

S is for Solve: Step 5: Now you need to arrange the data to SOLVE the formula. Put a box around your answer. Take two places past the decimal and Do not round your answer. m = PE gh 2500J (kg x m2/s2 9.8m/s2 x 42m = 5.83 kg

Practice 1.) What is the height of a 2 kg apple that has 400 J of energy? 2.) A 80 kg man is about to sky dive from 20,000 m in the air. What is his PE? 3.) A train with 456,000 J of PE, is about to go down a 400 m mountain, what is the train’s mass?

Practice 1.) What is the height of a 2 kg apple that has 400 J of energy? 20.4 meters 2.) A 80 kg man is about to sky dive from 2,000 m in the air. What is his PE? 1,568,000 J 3.) A train with 456,000 J of PE, is about to go down a 400 m mountain, what is the train’s mass? 116.33 kg