Physics 207 Practice Exam 4

1) A glass jar filled with air is sealed with a loose fitting lid all at 100 degrees C. Estimate the force required to remove the lid at 0 degrees C.
2) A jar at room temperature is fitted with a screw-on Aluminum lid which just fits if it is at 100 degrees C. Estimate the torque required to unscrew the lid at 23 degrees C.
3) An ice cube at 0 degrees C is dropped into a cup of coffee at 180 deg. F. Neglecting heat loss, estimate the final equilibrium temperature.
4) Electricity costs 6 cents per kilowatt-hour. You live in a windowless concrete house. Estimate your monthly heating bill.
5) Compare the typical molecular speed to the speed of sound for air under normal conditions.
6) A Carnot cycle operates with air at 100 cycles per second between 100 deg C and 0 deg C. In the isothermal expansion step, 1 cubic meter of air is expanded in volume a factor of 2. What is the maximum average power that can be produced?