A cold pack is a small plastic bag that can be used for minor injuries. Some cold packs can become very cold when a chemical reaction is activated inside the bag. Monica made a working model of such a cold pack, which is shown below.

Question

When the large plastic bag is squeezed with enough force, the smaller bag inside bursts. When it bursts, the liquid citric acid mixes with the sodium bicarbonate. This results in an endothermic chemical reaction which absorbs heat, making the bag feel cold to the touch.

When designing such cold packs for minor injuries, what should be a major emphasis in the design?
A.
The outer bag should be made of material flexible enough for comfort but durable enough not to leak.
B.
The outer bag should be made of a more durable material like glass so that it can be more easily stored for reuse.
C.
The inner bag should be designed in such a way that it is more difficult to burst than the larger outer bag.
D.
The inner bag should contain a liquid that, when mixed with the sodium bicarbonate, there is no resulting temperature change.

Answer 1

The best emphasis in the design of such a cold pack should be:

A. The outer bag should be made of material flexible enough for comfort but durable enough not to leak.

This option emphasizes the importance of both comfort and durability in the design of the cold pack. The outer bag needs to be flexible to conform to the user's body and comfortable to use, while also being strong enough to withstand the squeezing force without leaking, which is critical for the effectiveness and safety of the product. The other options do not prioritize these essential characteristics as effectively.