Physics H131: Problem Set #7

Chapter C9 Problem

• C9S.4: If you can consider some system as the sum of three smaller subsystems, how are the moments of inertia of the total system and the subsystems related? Make sure that the subsystems have masses that add up to the total mass.

Chapter C10 Problems

• C10B.4: Try to think of everything that happens, and subdivide the energy flows into heat and work. What happens to the heat shield tiles as the shuttle enters the atmosphere?
• C10S.6: What happens to the total kinetic energy in the collision? How can you calculate it? Use momentum conservation!
• C10R.1: (a) This is a simple exercise of plugging numbers into Eq.(C12.12). (b) Assume that all interior surfaces (walls, ceilings, floors) are covered with gypsum wallboard, including the extra interior wall. Don't forget to subtract the thickness of walls from the external dimensions when calculating the interior surface. This part of the problem requires unit conversion between several "american" (non-SI) units. How much thermal energy can all this gypsum store per unit temperature change? (c) When calculating the air volume you can neglect the volume of the gypsum in the interior wall. (d) Don't try to be too accurate in computing the volume of concrete in the walls. Taking the interior surface and multiplying with the given thickness should give a reasonably accurate approximation. (f) Think about your assumptions about the values of the inside and outside temperatures, about "heat leaks" that you neglected, etc.

Chapter C11 Problems

• C11T.3: How much latent "heat" do you need to melt the ice?
• C11T.5: What makes the egg hard? What controls the energy flow from the boiling water to the egg?
• C11B.1: Which criterion defines the (classical) turning points and separates (classically) allowed and forbidden regions?
• C11B.11: Read the text in section C11.4 to find the relevant numbers.
• C11S.5: Write down the complete energy balance. Don't forget about latent heat.
• C11R.2: How much energy do you get from burning one gallon of gasoline? How much extra energy do you need when travelling up the incline rather than on a level road? On which parameters does the answer to this question depend? Does the speed at which you drive up the incline matter? If not, why was the speed given? Which other quantity is affected by the speed? (Think of all the sources of k-work done on your car.) Thus, which information is transmitted to you when it is stated that the car drives up the incline at the same speed as it travelled horizontally before?