ENERGY

What do you think of when you hear the word ENERGY? Food Movement Doing things Working Sunlight

Why is energy so important to us? Where do they get the energy to go down the hill? Why is energy so important to us?

EVERYDAY ENERGY? What types of energy do you encounter everyday? How does energy get from one place to another? It will either transform or transfer.

So what is ENERGY?!?! Energy is NOT matter and is actually very difficult to define... Textbooks define it as … “The ability to do work” We will define it by providing examples of energy and the effects it has on objects. There are many different types of energy…

Types of Energy ALL energy can be classified as either Potential Energy or Kinetic Energy. Potential Energy is energy that is stored. Kinetic Energy is energy of anything that is in motion.

Gravitational POTENTIAL Energy (GPE) Gravitational Potential Energy (GPE) is the stored energy of an object resulting from the position of the object in a system. GPE relies on the height of the object in the system…the higher the object the more GPE it has. If you add GPE to KE you get Mechanical Energy (ME). ME= GPE + KE

Kinetic Energy (KE) Kinetic Energy (KE) - the energy of motion. The energy associated with moving objects is called kinetic energy (KE), and is often referred to as the most fundamental form of energy. The size of the KE is determined by an object’s speed and its mass.

Salem Nuclear Power Plant Nuclear Power- Nuclear power plants split the nuclei of uranium atoms in a process called fission. The sun combines the nuclei of hydrogen atoms in a process called fusion. Scientists are working on creating fusion energy on earth, so that someday there might be fusion power plants.

Chemical Energy vs. Nuclear Energy It is the energy that holds electrons together that move around the nucleus. Happens in the Electron Cloud The energy can be released when the bonds are broken. Small Amount of Energy released Examples Digestion, burning fossil fuels Nuclear Energy It is the energy stored in the nucleus of an atom. Happens in the Nucleus The energy can be released when the nuclei are combined or split apart. Large amount of Energy released Examples Sun,x-rays, Nuclear Power

What’s the Difference between energy transfer and energy transformation? Give an example of each. Energy transfer is when the same energy is transferred to another object. When you kick a soccer ball down the field with your moving leg! (transferring energy from your leg to the ball) Energy transformation is when one energy type changes into another type of energy. A rollercoaster that is stopped on top of the hill rolls down the track. (PE-KE)

Energy in Systems Energy can move from place to place or change from one type to another… Energy transformation – is changing from one type of energy into a different type of energy. Energy transfer - is how the same type of energy is passed from one object to another object.

Dropping Golf Balls ... You will drop a golf ball and a fuzzy ball from four different heights (25cm, 50cm, 75 cm and 100cm) looking for evidence of energy by a change that is produced by each one.

Let’s Investigate At each lab station you will find a piece of paper with 7 Questions and a set of directions from A-D. (Do NOT write on these sheets.) You must do these in order… so if some Questions come first, answer the question BEFORE going on to the direction steps!!! Answer the questions on the dry erase board neatly. You may discuss the answers as a group, but do NOT copy answers from other groups…write your own!!!

Set up a Data Table Make a data table One column for the golf ball and one column for the fuzzy ball. Use little ruler to measure the width of the crater in cm. Then Use the ruler to smooth the sand. Record your answers. Clean up when you are finished! Answer post lab questions. Heights Golf Ball Fuzzy Ball Height (cm) Width of Crater (cm) 25 50 75 100

Investigation Results 1.) The golf ball does not have any KE since it is not moving. It does not have the ability to move on its own due to its position (sitting in the sand) so it does not have any GPE. If KE = 0J and GPE = 0J then ME is also 0J!!! 2.) The golf ball now has GPE b/c it is above the ground… it now has a height of 25cm!!! It does not have KE though since it is not moving.

Investigation Results 3.) The golf ball got its energy from the person who picked it up and moved it to a height!!! The person TRANSFERRED energy to the ball from themselves when they lifted it!!! This energy came from the person’s muscles. The muscles got their energy from the food you ate. Tracing this flow of energy is called an ENERGY CHAIN.

Investigation Results 4.) The ball dropped from the highest point = 100cm caused the biggest crater. 5.) The variable that changed here was the MASS of the ball. Everything else remained constant (stayed the same). The craters produced by the hollow ball w/ less mass were smaller. Mass affects GPE and KE!!!

Investigation Results 6.) Both of the balls hit the sand at the same speed!!! (In other words, they fall at the same time!!!)…Watch I’ll show you… The difference between the two balls is the amount of energy!!! The more massive ball possesses more energy!!!

Investigation Results 7.) The big point you should have concluded is that MASS affects both GPE and KE. You should have also concluded that the higher the release point, the faster the ball will be traveling when it hits the sand. Gravity speeds up ALL falling objects at the same rate (9.8 m/s2). The greater the speed of the object when it hits the sand, the greater the KE.

LAW OF CONSERVATION of ENERGY

In the golf ball investigation, can we account for all the energy in the system? Basically, if we add up all the PE, KE and any friction, will it equal the total energy (TE) in the system? Yes, scientific evidence leads us to believe that ALL of the energy in any example can be accounted for! But it is not always easy in an open system.

LAW OF CONSERVATION of ENERGY Energy cannot be created or destroyed; it can only be transformed or transferred. Total Energy is all the energy in a system The TOTAL ENERGY (TE) will always stays the same!!! TE = PE + KE + heat

LAW OF CONSERVATION of ENERGY The TOTAL ENERGY of a system can be measured by adding PE + KE + Heat. TE = KE + PE + heat Q: Where does the heat come from??? A: Friction!!! (Rub your hands together and see what happens!!!)

LAW OF CONSERVATION of ENERGY TE will equal the GPE at the highest point in a system! TE=GPE at the highest point 100 Joules of energy to start 100 Joules of energy at the end! Equal at the mid point! “What you put in, is what you get out!” (TE) NEVER CHANGES in a system! A B C

LAW OF CONSERVATION of ENERGY Let’s look at the pendulum swing. Will it continue to swing with same amount of energy over time? Why won’t the beginning energy ever equal the end energy??? Hint: Can heat be contained in an open system? NO… please remember that energy is not destroyed, but some of it can escape from the system to the surroundings in the form of heat from the rope.

LAW OF CONSERVATION of ENERGY This is why no system will ever be 100% efficient… Meaning the beginning energy will never equal the end energy… There is no such thing as a frictionless system!!!

2. In an energy chain, only KE and GPE are to be included. AGREE DISAGREE As energy is transferred and transformed in a system, some of the energy is lost. Work is the same thing as energy. If something has a lot of energy, it also has a lot of power.

ENERGY CHAINS Since energy is transferred and transformed all the time, it is helpful to be able to track the “flow” of energy in systems. A map of what happens to energy, where it goes, and how it changes is called an Energy Chain. Energy chains can be created using words, pictures, arrows, or any combination of things that show the movement of energy in an example.

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?