Final answer:
A cold alcohol thermometer's column of alcohol drops before rising in hot liquid due to the glass expanding faster than the alcohol initially. Wine glasses produce a tone when rubbed because friction causes resonance at the glass's natural frequency.
Step-by-step explanation:
Explanation of Alcohol Thermometer Behavior
When a cold alcohol thermometer is placed in a hot liquid, the immediate contraction happens because the glass, which is more conductive, heats up and expands faster than the alcohol. As the glass expands, it temporarily creates more space for the alcohol than there was before, causing the level to drop. Soon after, the alcohol absorbs heat, expands, and the column of alcohol rises, indicating the increasing temperature of the hot liquid.
Resonance in Wine Glasses
Wine glasses can be set into resonance by moistening your finger and rubbing it around the rim of the glass because the friction between your finger and the glass causes it to vibrate at its natural frequency. A thin layer of water acts as a lubricant and facilitates a smooth interaction, allowing the glass to resonate and produce a musical tone.