Chapter 23, Problem 30A

You can determine wind direction if you wet your finger and hold it up into the air. Explain.

To determine

The method of finding the direction of air by wet finger.

Answer to Problem 30A

The cool side of finger determine the direction of air from which it comes .

Explanation of Solution

When the wet finger evaporates it feels cool, so in which direction the finger feeling cool it gives the direction of the air.

Conclusion:

The cool side of finger determine the direction of air from which it comes .