More Heat Waves

Honors Physics took time to look at the other side of heat exchange – when heat exchange promotes phase change. We really have to expand out definition of heat to include this phenomenon – heat is energy exchanged between objects at different temperatures or between objects at the same temperature if one of the objects is undergoing a phase change. Heat intake or outflow during a phase changes alters potential energy in a substance, not the kinetic energy or temperature of a substance. We contrasted the heat of vaporization with the heat of fusion and ran through some problems involving both temperature change and phase change. Tomorrow, we’ll finish going over those problems and discuss the methods of heat transfer – conduction, convection and radiation. We’ll also take a few moments to specifically outline what material from the heat chapter you will be likely to see on the midterm exam.

Physical Science B reviewed and summarized the wave material we’ve covered so far and then went over some practice problems for wave speed. Students were then given an additional set of practice for wave speed, frequency and period to work on in class. We will go over those problems tomorrow, if we have time after the lab activity, or during the next period we meet after the midterm. Tomorrow’s lab will allow you to model the properties and characteristics of waves that we have discussed so far and to calculate the speed of the waves that you create in class.

Physical Science E spent time contrasting the transverse waves we studied in lab with longitudinal and surface waves. We then looked in more detail at wave speed calculations and the inverse relationship between wavelength and frequency for waves. The electromagnetic spectrum was used as an example of this relationship – all EM waves travel the same speed in a vacuum (3 x 10⁸ m/s), so if a wave has a short wavelength, it has a high frequency (say the gamma rays), and if it has a long wavelength, it has a low frequency (radio waves). Tomorrow, more practice working problems with wave speed, period and frequency.

Physics F and G jumped back into heat with a discussion of the nature of heat and began an examination of the concept of specific heat. The specific heat definition was outlined and used to explain such phenomenon as a nice cool swimming pool on a hot summer day. Tomorrow, we will go over the homework problems and talk about how we physically determine the specific heat of materials – calorimetry.

Homework

Honors Physics A: None
Physical Science B: Read lab sheet and complete the wave speed packet
Physical Science E: None
Physics F and G: Complete Practice 10C #4,5