Week 21 (Jan. 15-19)

Reading: Heat and the First Law (Chap. 20)

Key Topics:
thermal energy, specific heat capacity, latent heat, the first law of thermodynamics, conduction, convection, and radiation of heat,

Homework Problems: Due next Tuesday, Jan. 24, at noon.

  1. Melting an ice cube: How much heat is required to vaporize a 1.0 kg ice cube initially at 0 deg. C? The latent heat of fusion of ice is 80 cal/gram and the latent heat of water is 540 cal/gram.
  2. Isobaric expansion of ideal gas: An ideal gas is enclosed in a cylinder with a movable piston on top. The piston has a mass of 8000 g and an area of 5.0 sq. cm. It is free to slide up and down, keeping the pressure of the gas constant. How much work is done as the temperature of 0.20 mol of gas is raised from 20 to 300 deg. C?
  3. Isothermal expansion of ideal gas: Five moles of an ideal gas expand isothermally at 127 deg. C to four times its initial volume. Find the work done by the gas and the thermal energy transferred to the system in Joules.
  4. Heat conduction: The right end of a bar of gold is in thermal contact with the left end of a bar of silver of the same length and cross-sectional area. The left end of the gold bar is maintained at 80.0 deg. C; the right end of the silver bar at 30.0 deg. C. When the system reaches steady-state, what is the temperature at the junction of the bars?
General College Physics