All About the Heat

Honors Physics reviewed for Thursday’s exam by going over the review material assigned for homework.  Tomorrow’s lab will allow you to investigate Boyle’s Law in more detail and you should also have time to ask any final questions about Thursday’s exam.  We will actually look at the behavior of gases later with the chapter on Thermodynamics and do lab work that will demonstrate the pressure, temperature and volume relationships more clearly (as well as relate them to work).

Physical Science B conducted a lab investigation that allowed students to examine the pattern of heat transfer between two substances at different temperatures and to calculate the amount of energy released by a fuel (candle wax).  For the mixing of hot and cold water, the symmetry of the plots was quite striking.  Since the identity of the substances was the same, they had the same specific heat.  For every morsel of heat energy the hot water transferred to the cold water,  the temperature changes produced in the water samples was the same.  The hot water lost the same amount of temperature as the cold water gained.  If the substances were not identical, we would not see the same pattern for temperature change, but the fact that the amount of heat lost by the higher temperature substance equals the amount of heat gained by the lower temperature substance would still be valid.  For the candle wax, the potential energy stored in the chemical bonds of the wax was transmitted to the water in the soda can (our makeshift calorimeter) and students were able to measure the amount of energy released by monitoring the temperature change of the water in the can.  Tomorrow, we will go over the lab more fully and also take time to review for Thursday’s exam.  Remember that the lab write up is due on Friday.

Physical Science E discussed the connection between heat, temperature and work.  An increase in an object’s temperature can be produced by the transference of heat, but it can also be altered by the object doing work or having work done on it.  The work is converted into internal energy that raises the temperature of the object.   So, an object can experience a temperature change through a couple of mechanisms – heat transfer or work.  In the next chapter we’ll see what happens when heat transfer or work does not produce a temperature change – the concept of change of state.

Physics F and G completed their discussion on the behavior of gases and moved on to a discussion of temperature.  Yes, this is in the next chapter, but it dovetails nicely with our current topic, so just chill.  The lab for this week will center on Boyle’s Law and allow you more time to reflect on the nature of gases. Exam on Monday, so be ready with questions for your day of review.

Homework

Honors Physics A: Read over lab sheet

Physical Science B: Complete MCAS Review and Chapter Review #28, 34, 37-39, 41

Physical Science E:  Chapter Review #28, 34, 37-39, 41

Physics F and G: Complete the 10.1 Section Review