1. In the book, it explains about destructive interference, which is about two similar waves but the crest of one wave joins briefly with the trough of the other meets, the amplitude decreases. But even if the destructive interference doesn't happen, I think that waves disappear because you didn't give the water, energy. The wave was caused because you tap the water with your finger. But you didn't tap the water again and again. So the water waves didn't have the energy to transfer and the amplitude decreases and the wave stopped.

2. Refraction occurs because waves travel at different speeds in different mediums. But humans don't. Because humans don't suddenly become fast in the water, it depends on theirselves. So humans don't bend when they enter a new medium.

3. Sound waves can move only through a medium that is made up of matter. For example, sound waves can travel through such as air, liquids, solid materials because these are all made up of particles. Sound waves cannot travel through a vacuum. In the vaccum sound experiment, the sound of the bell became quieter, so the bell was suspended.

1. Waves eventually come to an end, even if they do not get influenced by constructive or destructive interference.When the water drop first hits the surface of the water, it creates a wave that goes outwards in circles. The movement of the wave gradually decreases as more energy from the wave is used to move the still water around it. In the end, the wave stops moving.

2. When a straw is half-in and half-out of water, it looks split because the speed of the light changes when it encounters a new medium. However, we(people) are not influenced by this new medium. We are perfectly capable of controlling our speed. Thus, refraction does not work when people dive into water.

3. In the normal air we breathe, there are many particles. Sound is a type of mechanical wave that is produced by a vibrating object and travels through matter. Particles are a kind of matter. When Boyle pumped the air out of the sealed jar, the particles were withdrawn from it, leaving behind only a vacuum, an empty space consisting of none or very few particles. Sound waves need matter to vibrate against, but if this factor is removed, sound waves cannot occur. As a result of this, the sound grows smaller or dies out.

1. All the waves have their maximum length that they can reach. If they pass those maximum length then the waves will naturally vanish. If they continue to stay even though they pass their length then so many waves will stay as they are produced.

2. Refraction shows up because light travel in a different speed if the substances are different. However, our bodies stay is same speed, despite the substances that we meet changes.

3. Sound is the wave that can travel only through air, liquid, and solid. However when pumped out of the jar then sounds can't be trasported because there are no particles that can deliver sound.

1.

The book says 'when a 1m wave crest meets a 1m wave trough, the amplitudes cancel each other out'. Let's say the first amplitude was 2m. If that amplitude meets the surface, the amplitude will become 1m. This change will continue again and again until it becomes the same as the surface. This happens because a interference was made, that canceled out the amplitude.

2.

A refrection is made because light travel at different speeds in different mediums. But our body's speed does not depend on the midium they are traveling, it depends on us. So our body won't react as sames as light does when we travel in a different midium.

3.

A sound can only travel through a medium that is made up of matter, such as solid things, liquid, and air. But a vacuum is made out of few particles or none of them, and because of that, a vacuum is not a matter. So if a bell is suspended in a vacuum, the loud sound of the bell becomes quieter.

1. When your finger touches the water, not only one, but many waves form. Constructive interference makes the amplitude increase, and destructive interference makes the amplitude decrease. They must cause destructive interference because the amplitude decreases. But I don't understand the reason  the crest of one wave joins with the trough of the other.

2.  Light refracts in a new medium because light travels in different speed in different mediums.

Our body's speed does not change when we enter another medium, I mean, we can control our speed. It does not depend on the medium.

3. Sound waves travel through mediums. It cannot travel without mediums. In vaccum, there is no  medium to travel through. If sound waves cannot travel, we cannot hear the sound. So, in Boyle's sound experiment, the bell is suspended.