4. In some parts of the world people use spears in order to catch fish. Quite often when people try to do it for the first time they will miss, even if the fish is only a meter or so away. They quickly learn to not aim at the fish but just slight away from it.
i) Why do you think this is?
ii) Where do you think they will have to change their aim to? Above the fish, below the fish, to the left or to the right? Explain your answer using scientific terms.
i) The reason people initially miss the fish when using spears is most likely due to a phenomenon called refraction. Refraction occurs when light travels from one medium to another, causing a change in its direction. When light enters water from the air, it undergoes refraction as it travels through the water. This change in direction can make objects appear shifted or distorted when viewed from above the water's surface.
When we look at an object, our brain subconsciously adjusts for this refraction and allows us to accurately perceive the object's true position. However, when attempting to spear a fish underwater, this adjustment process becomes more challenging. Our brain may instinctively aim directly at where we visually perceive the fish to be, without considering the refraction-induced shift.
ii) To compensate for refraction and successfully spear the fish, people will have to change their aim slightly away from the fish. Specifically, they need to aim below the perceived position of the fish due to refraction. This adjustment is necessary because refraction causes the fish to appear higher in the water than its actual position. By aiming slightly lower than the perceived position, they increase the chances of the spear hitting the fish accurately.
Overall, by understanding the scientific concept of refraction and how it affects the perception of objects underwater, people can adjust their aim to successfully catch fish using spears.