Task6 練習問題 2_2

Have you ever ridden an airplane and it suddenly became shaky? This situation would make most passengers uncomfortable, and some might even wonder what is happening. This is what we call air turbulence. Turbulence is one of the two motions of liquid and gas that is composed of unorganized swirls. It is always chaotic and very sensitive to disruptions. But do you know what causes air turbulence? To further understand how turbulence happens, let us discuss the two opposing forces in a flowing liquid or gas.

Let us talk about the first force, which is inertia. Inertia is the tendency of a liquid or gas to keep moving, which often results in instability. Substances like water or air are more prone to inertia because they are less thick. For example, imagine you are pouring water into a glass. You will notice that the water flows in different directions. It is important to remember that the more inertia there is in a substance, the higher the chance of developing turbulence.

Now, let us talk about the second force, which is viscosity. Viscosity works against the disruption that makes the flow of liquid or gas more stable. Substances that have a thicker consistency are usually composed of more viscosity than inertia. For instance, if you pour honey into a jar, you will notice that it flows in almost the same direction. That is why the flow of pouring honey is more stable as compared to the flow of water.

Have you ever tried reading a book while traveling by car, boat, or train and then suddenly felt dizzy? This is what they call motion sickness. About one in three people is prone to this. But do you know why so many people experience motion sickness? Up to this day, scientists are not a hundred percent sure about the reason behind it. However, one theory says that motion sickness has something to do with mismatched sensory signals. Sensory signals are the messages our brain receives through our sensory organs, such as our ears, eyes, and nose. When traveling in a car, our body gets two different messages that cause our body to feel sick. Let us look into more details about these two messages.

The first message our body receives is that we are seeing the inside of the vehicle or the book we are reading. We generally see them as if they are not moving. Our eyes are responsible for this message.

The second message we receive is that we are accelerating. Our ears are sending our brains this message. Yes, our ears have another function aside from hearing. Our ears also give us a sense of balance and movement. That is why, when we move, they tell our brain which direction we are moving in. So when we travel in cars, our ears send our brains a message that we are moving.