What makes a sealed pressure cooker prepare food more quickly?

Correct Answer: It raises the boiling point of water by increasing the pressure inside the cooker.

Step-by-Step Explanation:

1. Understanding Boiling Point and Vapor Pressure:
A liquid boils when its vapor pressure becomes equal to the external surrounding pressure. Under normal atmospheric pressure at sea level, water boils at a standard temperature of 100 °C (212 °F).

2. Pressure Build-up in a Sealed Container:
When water is heated inside a tightly sealed pressure cooker, the resulting steam cannot escape. As steam accumulates in the trapped space, it exerts an increased force per unit area, significantly increasing the pressure inside the cooker above normal atmospheric levels.

3. Elevation of the Boiling Point:
Because the internal pressure is substantially higher, liquid water requires a higher temperature for its vapor pressure to match the surrounding internal pressure. As a result, the boiling point of water increases (typically reaching around 120 °C or 250 °F).

4. Faster Cooking at Higher Temperatures:
Since water remains in the liquid state at a higher temperature instead of boiling away as steam, food cooks in liquid and steam that is considerably hotter than 100 °C. Chemical reactions in cooking progress much faster at these elevated temperatures, drastically reducing the overall cooking time.

Conclusion:
Therefore, a sealed pressure cooker cooks food faster because it raises the boiling point of water by increasing the pressure inside the cooker.