# Week 8

Fall Break; no class Monday and Tuesday

Read: Work and Weight (Chap. 9); Kinetic and Potential Energy (Chap. 10)
Quiz: None.

Homework:

Joule heating/calorimetry lab. This week, you will be attempting to measure the specific heat capacity of water by observing the rate of temperature change when the water is heated using a resistive heating element. Place enough water in an insulated calorimetry cup so as to cover the cartridge heater (approximate resistance 14 ohms). Insert a stainless steel temperature probe into the water. You will be reading the temperature as a function of time using logger-pro software. You will use a variable power supply to drive about 1 ampere of current through the heater, and you will use the joule-heating formula, P = I^2 R, to determine the number of watts of heat delivered to the water. When everything is ready, begin collecting temperature data. Turn on the heater, and watch the temperature rise for at least 10 or 15 minutes. Then turn off the power supply and watch it cool back to room temperature. Interpret your heating (and cooling) curves, and determine the specific heat of water. Compare your result to that of a reputable source. Explain any discrepancies in terms of systematic errors in your procedure, if possible.

Chapter 9 (3 videos):

Chapter 10 (3 videos):

Physics 2