1. A bottled beverage at 0 °C has ice in it. You want to melt the ice by placing it in water at 20 °C. Estimate how much ice will be melted in one minute. Assume that the glass walls of the bottle are 2.5 mm thick and that 300 cm2 of the bottle are in contact with the water.
2. A small water proof electric motor is being tested. The motor is in a container with some ice and water, which are initially in equilibrium. (The situation is similar to Figure 6.3 except that the rotating shaft, the generator, and wires are replaced respectively by wires, a motor, and a shaft.) 60 watts of power are delivered to the motor for 40 s while the motor turns a shaft which causes a 25 kg mass to be raised vertically by 8.0 m. The contents of the container then come to equilibrium.
The motor is the system in parts (a), (b), and (c).
(a) What is the value of W for the process?
(b) What is the value of ΔU for the process?
(c) What is the value of Q for the process?
(d) How many grams of ice were melted during the process?