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

A mountain biker rides down a 42m high mountain with 2500 J of GPE A mountain biker rides down a 42m high mountain with 2500 J of GPE. What is the mass of the mountain biker? D U F A S PE=2500 m=? g=9.8 h=42 J Kg m/s m PE=m*g*h m= PE/(g*h) m= 2500J/(9.8m/s * 42 m) m= 6.07 kg

Think about the number line: Scientific Notation Think about the number line: + - -2 -1 1 2

Here’s what that means… Scientific Notation When you see a number like: 3.46 E-4 m Come up on your calculator… Here’s what that means…

Scientific Notation 3.46 E-4 … The E-4 means x10-4 And here is how you translate that into a number. The exponent (-4) tells you how many times to move the decimal point (4). And because it is negative (-), to move it left!)

Scientific Notation So for 3.46 E-4 g You will move the decimal point 4 times to the left. (negative is to the left on the number line!!!) = .000346g Make sure you put units on it also! =.000346g

Scientific Notation Let’s practice: Change 4.86 E3 kg into a regular number… Need to move the decimal 3 times and to the right because the 3 is positive. = 4860 and don’t forget units! = 4860 kg

Scientific Notation YOUR TURN: ANSWERS: 1.) 9.325 E-2 m 2.) 2.1903 E4 kg 3.) 7.473 x10-6 g 4.) 3.801 x105 cm3 ANSWERS: 1.) .09325 m 2.) 21903 kg 3.) .000007473 g 4.) 380100 cm3

Solving Energy Problems h pg 299 (1-4) m = PE h = PE g*h g*m do this 1st do this 1st

MASS kilo hecto deka gram deci centi milli kg hg dg g cg mg 1,000 100 kilogram hectogram dekagram gram decigram centigram milligram 1,000 100 10 1 0.1 0.01 0.001