The Sense of Touch
We know from experience that some bodies are hotter than others. Ice is cold, while boiling water is hot. Usually, we use our sense of touch to decide this. However, is our sense of touch reliable?
Activity: The Three Container Experiment
To test the reliability of our touch, consider this classic experiment with three containers of water.
Steps:
- Container A: Hot water.
- Container B: Lukewarm (mix of hot and cold) water.
- Container C: Ice-cold water.
- Dip your right hand in A (Hot) and left hand in C (Cold) for 2 minutes.
- Now, dip both hands simultaneously into B.
Observation:
- The right hand (coming from hot water) feels that water in B is cool.
- The left hand (coming from cold water) feels that water in B is warm.
Conclusion: Since the same water cannot be both cool and warm at the same time, this proves that our sense of touch is relative and unreliable for scientific measurement. We need a device to measure hotness accurately.