Saturday, 26 July 2014

Think 2

QUESTION: KEYWORDS: shiver, feel cold

GROUP DISCUSSION:
My Answer:
When you come out of the pool, water on your body evaporates. At the same time, taking Thermal energy away from your body. On a hot day, the surroundings have more thermal energy, thus, increasing rate of evaporation of the water on your body while taking away more Thermal energy from your body. When your body has less Thermal energy, the molecules will move slower, causing a drop in temperature, making our body feel cold. 

Standard 2mark answer: (KeyPoints)
-(Why do you feel cold):  
When I come out of the water, the water droplets on my body evaporate, at the same time, taking heat away from the body. When my body lose thermal energy, I feel cold. 
-(Why do you shiver):      
As the water evaporates, there is a change of state from liquid to gas. This change of state requires a lot of thermal energy. As more thermal energy is removed from my body within a shorter period of time, I shiver.

WHY DO WE SHIVER? (At Micro-Level)
The human body needs to stay at the same temperature(37degrees Celsius) to survive. When you feel cold, sensors in your skin send messages to your brain telling you a need to warm up. Your brain then sends messages to nerves, telling your muscles to tighten and loosen rapidly which is what we call shivering. It does this because when muscles move they generate heat.
When you put towel/go back to the swimming pool, you are preventing water on your body from evaporating. That is why you would stop feeling cold.




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