2 Learning Goals Identify energy as potential or kinetic. Use caloric values to calculate the kilocalories (Cal) in a food. Given a temperature, calculate a corresponding temperature on another scale. Use specific heat to calculate heat loss or gain, temperature change, or mass of a sample. Identify the physical state of a substance as a solid, liquid, or gas. Describe the changes of state between solids, liquids, and gases; calculate the energy involved.
3 Energy makes objects move. makes things stop. is needed to “do work”. Energy
7 Learning Check Identify the energy as potential or kinetic. A. roller blading B. a peanut butter and jelly sandwich C. mowing the lawn D. gasoline in the gas tank
8 Solution Identify the energy as 1) potential or 2) kinetic. A. roller blading (kinetic) B. a peanut butter and jelly sandwich (potential) C. mowing the lawn (kinetic) D. gasoline in the gas tank (potential)
9 Heat is measured in joules or calories Joules (J) = 1 calorie (cal) (exact) 1 kJ = 1000 J 1 kilocalorie (kcal) = 1000 calories (cal) Units for Measuring Energy or Heat
10 Examples of Energy In Joules
11 Learning Check How many calories are obtained from a pat of butter if it provides 150 J of energy when metabolized?
12 Solution How many calories are obtained is a pat of butter if it provides 150 J of energy when metabolized? Given: 150 J Need: calories Plan: J cal Equality: 1 cal = J Set Up:150 J x 1 cal = 36 cal J