Unit 07 “Work, Power, Energy and Energy Conservation” The Conservation of Energy

Define Conservation: To save. Not changed. Remains the same. Convert: Change from one form to another form. Conversion Energy: The ability to do work. IF work is done, energy is used. If an object or person has energy, it can do work! Energy has two categories: Mechanical Energy Kinetic Energy Potential Energy Non-Mechanical Energy Chemical Energy Thermal Energy Electromagnetic Energy Nuclear Energy In total there are 5 types of energy: Mechanical, Thermal, Electromagnetic, Nuclear, Chemical

The Conservation of Energy states: Energy cannot be created or destroyed. It can only be converted from one form to another. Equation There are many equations for Energy. We will learn the equations for kinetic and potential energy later in this unit. Units Joule (metric system) calorie (English system) Conversion Factors 1 calorie = Joules 1 kilocalorie = 1000 calorie 1 Calorie = 1 kilocalorie

Electromagnetic Energy Wave energy due to magnetic and electric fields “Light waves”  Microwaves  UV waves  X-Rays  Visible Light  … and more! Thermal Energy Energy stored in fast moving molecules which creates heat  Heat  Can be caused by friction Chemical Energy energy stored in chemical bonds  Food  Fossil Fuels (gas, oil) Types Of Energy Conservation of Energy: Mechanical Energy  Kinetic Energy  The Energy of motion  Potential Energy  The Energy of position Nuclear Energy Energy stored in the nucleus of an atom  Fission (like the atomic bomb)  Fusion (like the sun) Total Energy is conserved! Energy is never lost! Energy is converted from one form to other!

Energy is conserved. This means the ________ energy stays the _________. But the energy can _________ from one form to another. This is also called ____________ from one form of energy to another. totalsame changed converting

Example 1 Example 2 Example 3 The plant converts Electromagnetic Energy (visible light) from the sun into chemical energy (food) The car converts gasoline (chemical energy) into movement (kinetic energy) Electromagnetic Energy  Chemical Energy  Chemical Energy  Kinetic Energy

Stay Healthy With Physics! People are a great example of energy conversion! People need approximately _____________Calories a day (that is __________kilocalories) That Energy is used to keep us __________! You must eat enough food to keep your body __________! Eating _________food means you don’t give your body enough ________to be _________. You may be __________, have _________ problems or be in a ______________ often! Eating _________ food means your body will store that food as ____________ energy in your body. We store this energy as “________”. This can hurt your body too. If you exercise (play sports) you should eat an extra __________ Calories a day! You need it the extra _________ to do the extra _______ when you play. Eating the right amount of food and the right kinds of food will help you stay healthy! 2000 ALIVE healthy lessenergyhealthy weakheartbad mood more chemical fat 500 energywork

Caffeine does NOT give you energy; there are not “calories” in caffeine! Caffeine is a drug that causes your heart to beat faster! More work for you heart, no extra energy to use … not good! Don’t drink too much caffeine or take other drugs that “help you get energy”. The only way to get energy is to EAT FOOD! Does Caffeine (like in soda and coffee) give you energy?

Vitamins and minerals also do not give your body energy. They help you do digest food (to get energy) and keep parts of your body healthy. But they do not give you energy. Only chemical energies such as carbohydrates and fats will give your body the energy it needs to do work!

The Energy Needs Of People Why do our bodies need 2000 Calories a day? When you sleep, your body used 72 Calories/hour!!! If you slept all day, you would use 1,750 Calories! That’s almost 2000 Calories! Let’s see what work our body does with all that energy!

Energy In Energy Out Chemical Energy Food Kinetic (Mechanical) Movement - muscles (running, walking, exercise, talking) Heart pumping Lungs breathing Growing metabolism Chemical Brain (chemicals to think and work) Sweat Digestion Poopies and peepies Thermal Heat (your body stays at 98.7 o F) Electromagnetic Brain (thinking) Signals to muscles