On a camping trip, your friend tells you that fluffing up a down sleeping bag before you go to bed will keep you warmer than sleeping in the same bag when it is still crushed from being in its storage sack. Explain why this happens. (hint: a large amount of air is presnt in an uncrushed sleeping bag)

Absence of air in uncrushed sleeping bag

Explanation:

A fluffy bag consists of air. Air is an insulator of heat and hence when a person sleeps in it, the heat of the body does not escape the fluffy bag. Due to this reason, once a fluffy bag gets heated, it remains heated for a longer period of time and the person sleeping in it does not feel the cold.

While in crushed bag, air is absent thus a person sleeping in a crushed bag loses his body heat soon and starts feeling cold.