Physics 14: 5-8 Heat Transfer and Phase Change

Homework

Reading Preparation
Key Equations
WebLecture
Study Activity
Chat Preparation Activities
Chapter Quiz
Lab Work

Reading Preparation

Text Reading: Giancoli, Physics - Principles with Applications, Chapter 14: 5-8

Study Points

14:5: We pump heat energy into a substance to get it to change temperature. When it reaches a phase change, we continue to pump energy into it, but the temperature doesn't change, because all the energy is going into the phase change. This energy is called latent heat energy. Different materials have different latent heats, just as they have different heat capacities. When we calculate the heat necessary to raise the temperature of a given amount of some substance through a phase change, we have to total the heat added for the temperature change with the heat added for the phase change.
14:6: Conduction is the flow of heat energy from one area or substance to another through direct contact. The bottom of a pan sitting directly on a hot stovetop is heated by conduction.
14:7: Convection is the flow of heat energy because the hot substance itself moves to a new location. Water near the bottom of our pan on the stove is heated, expands, and moves upward through cooler water, carrying its heat with it.
14:8: Radiation is the flow of energy by electromagnetic waves. Unlike conduction and convection, radiation does not require matter for the transmission of energy.

Key Equations

Latent Heat required for phase change: $\begin{array}{l} Q = mL \end{array}$
Thermal transfer rate (Conduction) $\frac{Q}{t} = kA \frac{T_{1} - T_{2}}{l}$
k = Thermal conductivity value for substance
A = surface area
Thermal transfer rate (Radiation) $\frac{Q}{t} = ϵ σ A ({T_{1}}^{4} - {T_{2}}^{4})$
ε = emissivity
σ = Stefan-Boltzmann constant = 5.67 * 10^-8 W/m²*K⁴

Web Lecture

Read the following weblecture before chat: Heat Transfer Mechanisms and Phase Changes

Study Activity

Play with the State of Matter exercise below. What happens during a phase change?

Physics simulation Java Applets are the product of the PHET Interactive Simulations project at the University of Colorado, Boulder.

Chat Preparation Activities

Forum question: The Moodle forum for the session will assign a specific study question for you to prepare for chat. You need to read this question and post your answer before chat starts for this session.
Mastery Exercise: The Moodle Mastery exercise for the chapter will contain sections related to our chat topic. Try to complete these before the chat starts, so that you can ask questions.

Chapter Quiz

Required: Complete the Mastery exercise with a passing score of 85% or better.
Go to the Moodle and take the quiz for this chat session to see how much you already know about astronomy!

Lab Work

If you want lab credit for this course, you must complete at least 18 labs; you may complete more if you are preparing for the AP exam.. One or more lab exercises are posted for each chapter as part of the homework assignment. We will be reviewing lab work at regular intervals, so do not get behind!

Lab Instructions: Specific Heat

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Physics

Chapter 14: 5-8 Assignment