Lecture_05_100511

# Lecture_05_100511 - Lecture 5 Energy Goal Identify energy...

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Lecture 5: Energy Goal: Identify energy as potential or kinetic energy and understand the units of energy. Be able to convert temperature from one scale to another. Use specific heat to calculate heat loss or gain, temperature change or mass of a sample. Outline (Timberlake Chapter 2.1-2.3): ± Energy (2.1) ± Temperature (2.2) ± Specific Heat (2.3) Problems for Extra Practice: 2.3, 2.5, 2.9, 2.11, 2.13, 2.15, 2.17, 2.19, 2.21

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Energy Energy – makes objects move – makes things stop – is needed to “do work” Work is done when – you climb – you lift a bag of groceries – you ride a bicycle – you breathe – your heart pumps blood – water goes over a dam
Potential Energy Potential energy is energy stored for use at a later time. Examples: • water behind a dam • a compressed spring • chemical bonds in gasoline, coal, or food

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Kinetic Energy Kinetic energy is the energy of matter in motion. Examples: • swimming • water flowing over a dam • working out • burning gasoline
Learning Check Identify each of the following as potential energy or kinetic energy. A) A slice of pizza B) Jogging C) A gallon of gas in a gas tank D) An car speeding down the road

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Heat and Units of Energy • Heat is defined as energy the flows from a warmer object to a cooler one • Heat is associated with the motion of particles • Heat is measured in joules or calories. – 4.184 joules (J) = 1 calorie (cal) (exact) – 1 kJ = 1000 J – 1 kilocalorie (kcal) = 1000 calories (cal)
Examples of Energy Values in Joules

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How many calories are obtained from a pat of butter if it provides 150 J of energy when metabolized? 1)
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Lecture_05_100511 - Lecture 5 Energy Goal Identify energy...

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