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Section 10.2 The Flow of Energy 1.To understand how energy flow affects internal energy How much energy is there in a substance? 2.To understand how heat.

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Presentation on theme: "Section 10.2 The Flow of Energy 1.To understand how energy flow affects internal energy How much energy is there in a substance? 2.To understand how heat."— Presentation transcript:

1 Section 10.2 The Flow of Energy 1.To understand how energy flow affects internal energy How much energy is there in a substance? 2.To understand how heat is measured What are the units of energy? 3.To understand how the flow of heat changes temperature How does an amount of heat gained or lost relate to a change in temperature? Objectives

2 Section 10.2 The Flow of Energy A. Thermodynamics Thermodynamics – the study of energy First law of thermodynamics –Energy of the universe is constant or –Energy can neither be created nor destroyed Where does the energy come from and go to in a basketball game?

3 Section 10.2 The Flow of Energy Internal Energy, E – sum of kinetic and potential energies of all the “particles” in a system A. Thermodynamics –Internal energy can be changed by two types of energy flow: Heat (q) Work (w) – a force acting over a distance  E = q + w I can warm a beaker of water with my hands or I can push it across the bench – which is q and which is w?

4 Section 10.2 The Flow of Energy Thermodynamic quantities always consist of 3 parts: A. Thermodynamics –A number (magnitude of the change) –A unit of energy –A sign (indicates the direction of flow in or out of the system) ΔE = -145kJHeat is given off - exothermic ΔE = + 377kJHeat is absorbed - endothermic

5 Section 10.2 The Flow of Energy

6 Section 10.2 The Flow of Energy B. Measuring Energy Changes The common energy units for heat are the calorie and the joule. –calorie : the amount of energy (heat) required to raise the temperature of one gram of water by 1 o C. –Joule : 1 calorie = 4.184 joules How many Joules does it take to raise the temperature of 1 gram of water by 1 o C? 1000 calories = 1kcal = 1 Calorie

7 Section 10.2 The Flow of Energy B. Measuring Energy Changes

8 Section 10.2 The Flow of Energy B. Measuring Energy Changes Specific heat capacity is the energy required to change the temperature of a mass of one gram of a substance by one Celsius degree. High Specific Heat Capacity of Water

9 Section 10.2 The Flow of Energy B. Measuring Energy Changes To calculate the energy required to raise the temperature of a substance: Q = s x m x  t


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