Chapter 15 Energy Table of Contents Topic 1
Chapter 15: Energy
Table of Contents � Topic 1: Types of Energy �Kinetic Energy and Potential Energy � Topic 2: The 6 Forms of Energy �Mechanical, Thermal, Chemical, Electrical, Electromagnetic, Nuclear � Topic 3: Law of Conservation of Energy �“Energy cannot be created or destroyed” � Topic 4: Energy/Mass Relationship �E=mc 2
15. 1 Energy and It’s Forms � Energy – The ability to do work. � Energy is measured in Joules. � W = F x d (Therefore) Energy is related to “Work” Energy = F x d **Work is the transfer of energy** A The sun gives off energy in the form of heat and light. B Plants convert this heat and light energy into food that we can process and eat. C People convert food energy into muscle movement
There are 2 GENERAL forms of Energy…
Energy Type 1 Types of Energy Kinetic Energy - Energy of motion. KE = ½ mv 2 **Some KE trends to know: �When the mass is doubled, the KE is doubled. �When the velocity is doubled, the KE is quadrupled. Kinetic Energy is the energy contained in any moving object
Kinetic Energy Math Practice 1. A 70. 0 -kilogram man is walking at a speed of 2. 0 m/s. What is his kinetic energy? Equation: KE = m = v = 2. A 1400 -kilogram car is moving at a speed of 25 m/s. How much kinetic energy does the car have? Equation: KE = m = v =
3. A 50. 0 -kilogram cheetah has a kinetic energy of 18, 000 J. How fast is the cheetah running? (Hint: Rearrange the equation to solve for v. ) Equation: KE = m = v =
4/10 Warm Up A 65 Kg linebacker has a kinetic energy of 12, 000 J. How fast is the linebacker running? Equation: KE = m = v =
4/10 Agenda � Warm Up � Notes: Types of Energy – Potential Energy �Kinetic Energy and practice �Potential Energy and practice HW: Pages 1 -2
There are 2 forms of Energy…
Potential Energy Type 2 Energy stored as a result of object’s position **PE becomes KE when the object starts moving. There are two types of potential energy. 1. Gravitational Potential Energy (GPE) ○ GPE depends on the height of an object. It increases as the object is raised up. “G”PE = mgh (g = 9. 8 m/s 2) 2. Elastic Potential Energy (EPE) ○ EPE is the potential energy of an object that is stretched or compressed (springs) This diver has gravitational potential energy as she stands at the end of a diving board.
Potential & Kinetic Energy are Connected!
� Math practice 1. What is the gravitational potential energy of a diver who has a mass of 61 kg standing on a platform that is 8 m off the ground? 2. What is the gravitational potential energy of a cat that weighs 40 N standing on a table that is 0. 8 m above the ground?
Forms of Energy There are 6 major forms of energy
Forms of Energy 1. Mechanical Energy- The energy associated with the motion and position of everyday objects. **ME is NOT limited to machines. ME = KE + PE EX: speeding trains, more below
Forms of Energy 2. Thermal Energy – The total PE and KE of every atomic particle in an object. ○ When an object’s atoms move faster, its thermal energy increases and the object becomes warmer. Remember the Kinetic Theory of Matter
Forms of Energy 3. Chemical Energy stored in the chemical bonds of a compound. When the bonds are broken, the released energy can do work. EX: burning wood, batteries This family is using the chemical energy of burning wood to produce thermal energy for heating marshmallows
Forms of Energy 4. Electrical Energy - energy associated with electric charges. - EX: lightning, CD players 5. Electromagnetic Energy - A form of energy that travels in the form of waves - EX: visible light, X-rays
Forms of Energy 6. Nuclear Energy - The energy stored in an atom’s nucleus ○ EX: Nuclear fission: releases energy by splitting the nucleus ○ Ex: Nuclear fusion: releases energy when small nuclei combine to form a bigger nucleus Energy released
Match the Energy form to the Description Write answers somewhere on your notes slides…. ___1. Falling rocks from the top of a mountain ___2. Release of energy from the Sun ____3. (a) Mechanical (b) Electrical ____4. Batteries (c) Heat ___5. The energy that runs a refrigerator (d) Radiant ____6. Nuclear fission reactors (e) Chemical ____7. The rumble of thunder from a storm ____8. Rubbing your hands together ____9. Gasoline ___10. Food before it is eaten ___11. Lightning (f) Nuclear
4/11 Warm Up 1. What is the gravitational potential energy of a ball with weigh of 3 Kg that is dropped 15 m off the ground? PE=mgh 2. The same ball is now dropped and begins falling. What is the Total Mechanical Energy of the ball after it has fallen 10 m (still 5 m above the ground) and travelling 12 m/s? Hint: Use ME=KE+PE
4/11 Agenda � Warm Up � Check HW � Notes: Conservation of Energy HW: Pages 3 and 4 Test Monday
15. 2 Energy Conversion and Conservation Energy Conversion �Energy can be converted from one form to another form. �When energy changes forms, the total energy remains unchanged. Energy is converted from one form to another as this match is lit.
Conservation of Energy � The Law of Conservation of Energy: “Energy cannot be created or destroyed” �In a closed system, during a reaction, the amount of energy at the beginning is the same as the amount of energy at the end. �Gravitational potential energy is converted to kinetic energy as the object falls. ie: 1. 5 kg oyster at height of 30 m Some gulls use energy conversion to obtain food by dropping oysters onto rocks.
Energy Conversion Calculations Conservation of Mechanical Energy (KE+PE)beginning = (KE+PE)end 1. A 15, 000 -kg roller coaster is traveling 75 m/s entering a loop (at position 1) and begins up a loop. Calculate the GPE the roller coaster has at the top of the loop (position 3). (You can ignore the effects of friction. )
Energy Conversion Calculations Conservation of Mechanical Energy (KE+PE)beginning = (KE+PE)end 1. A 15, 000 -kg roller coaster is traveling 75 m/s entering a loop (at position 1) and begins up a loop. Calculate the GPE the roller coaster has at the top of the loop (position 3). (You can ignore the effects of friction. )
2. a. A diver with a mass of 70. 0 kg stands at the top of a 3. 0 -m- high diving platform. Calculate his potential energy relative to the water surface while standing on the platform. (Hint: Assume the diver's initial vertical speed after diving is zero. ) 2. b. Calculate his speed when he enters the pool.
4/12 Do Now A 15 kg hypnotist’s pendulum moves with a velocity of 1. 5 m/s at the lowest point. Use the conservation of energy to determine how high up the pendulum travels. Challenge: Ignore the mass of the pendulum!
4/12 Agenda � Do Now � Review Homework � Do # 2 and 7 on the HW � Finish Notes Packet �E = mc 2 and Practice HW: Pages 5 and 6
3. A pendulum with a 1. 0 -kg weight is set in motion from a position 0. 4 m above the lowest point on the path of the weight. What is the kinetic energy of the pendulum at the lowest point? (Hint: Assume there is no friction. ) m= v= h= g=
Conservation of Mechanical Energy (KE+PE)beginning = (KE+PE)end 1. A 15, 000 -kg roller coaster is traveling 75 m/s entering a loop (at position 1) and begins up a loop. It gets stopped at the top of the loop. How high does the roller coaster go at the top of the loop (position 3). (You can ignore the effects of friction. )
E = mc 2
Energy and Mass Matter Einstein’s theory of relativity E = mc 2 �E = energy m = mass c = speed of light �Energy and mass are equivalent, and can be converted into each other. �Energy gets released as matter is destroyed, and matter can be created from energy. �The speed of light is a very large number, 3 x 108 m/s, and it is squared. Energy Think about our bodies using food to GROW!
Energy and Mass �A tiny amount of matter can produce an enormous amount of energy ○ 1 g of TNT = 2931 J of energy �In nuclear fission (splitting atoms) and nuclear fusion (creating atoms), large amounts of energy are produced from very small amounts of matter. � The law of conservation of energy has been modified to state that both mass and energy are conserved together.
2 problems E = mc 1. A sugar cube has a mass of 4. 2 g. If the mass of the sugar cube is converted into energy in your body, how many joules of energy would be produced? 2. How much mass M would you need to produce an energy E = 1020000 joules?
4/4 Agenda � Do Now and check HWx 2 � Go over HW � Quiz � Finish Notes Packet �E = mc 2 and Practice �Types of Energy HW: Finish worksheets from today
4/5 Do Now In your own words… 1. Explain how Geothermal Energy works? 2. Explain how a Hydroelectric Dam works.
4/5 Agenda � Do Now and check HW � Go over HW � Kahoot Quiz HW: Study!
4/8 Do Now 1. Write down 2 things you found especially interesting and/or memorable about yesterday’s film about renewable energy 2. If the USA could only use one of the Renewable Energy types you saw yesterday, which would be the best fit for the USA? Why?
4/6 1. 2. 3. 4. 5. Agenda Do Now Turn in Do Now Sheets Hand back work Go over tests Visit Linfen, China https: //www. vice. com/video/toxic-linfen-china
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