## Physics: Principles with Applications (7th Edition)

a. The sealed pressure cooker, with fixed volume and contents, experiences a rise in pressure as the temperature increases (see the ideal gas law). It is a good assumption that there is water present. From Figure 13-22, we see that the boiling point of water increases at higher pressure. So, the water boils at a temperature higher than the normal $100^{\circ}C$, which cooks the contents faster. b. At high altitudes, the atmospheric pressure is less than the standard value at sea level. From Figure 13-22, we see that the boiling point of water decreases at lower pressure. So, the water boils at a temperature lower than the normal $100^{\circ}C$, which cooks the pasta more slowly. c. No, it is actually easier to boil water at high altitude. From Figure 13-22, we see that the boiling point of water decreases at lower pressure. It takes less heat to bring water to the (lower) boiling temperature.