Phy 132 – Assignment 13 A. B. 1. a. Hold a piece of metal over a flame, or put an egg in a hot frying pan, or … (There are thousands of possible answers.) b. Put an ice cube in a hot frying pan. (If kept well stirred, the ice/water mixture stays at 0°C until completely melted. As energy is added, the internal energy goes up, but the molecules are not gaining kinetic energy, so the temperature stays the same. Rather, the energy goes into breaking bonds between molecules, increasing a form of potential energy.) 2. C. D. 1. a. One of many possible answers: Start a fire by rubbing two sticks together. The work done by friction, not heat flow, raises a stick’s internal energy and its temperature. b. Ride in an elevator. Work is done on you as you are lifted, but it increases an external form of energy, having no effect on internal energy or temperature. 2. E. 1. a. -100 J: ΔEint = Q + W. Q = 0 is the definition of the word adiabatic. (No heat flow.) There is 100 J of work, and W is negative when work is done by the gas. Or, think of the sign this way: As the gas expands, it gives energy to the outside world, perhaps turning the wheels of a car. Since energy is flowing out, the internal energy must be decreasing, and Δ(anything) is positive for an increase, negative for a decrease. b. 0 J: ΔEint = nCVΔT. ΔT = 0 is what the word isothermal means. (No temperature change.) 2. F.