In which situation do water molecules move faster: in a hot cup of coffee or in a cold cup of coffee?

• A. In a hot cup of coffee
• B. In a cold cup of coffee
• C. Molecules move at the same speed in both
• D. Molecules do not move in either

Answer: (A)

Verified step by step guidance

1. Understand that the speed of water molecules is related to their kinetic energy, which depends on temperature.
2. Recall that temperature is a measure of the average kinetic energy of molecules in a substance.
3. Recognize that in a hot cup of coffee, the temperature is higher, so the water molecules have more kinetic energy and move faster.
4. In contrast, in a cold cup of coffee, the temperature is lower, so the water molecules have less kinetic energy and move slower.
5. Therefore, water molecules move faster in a hot cup of coffee compared to a cold cup of coffee.