Discovery Activities + Connections

On our last science class we tested how waves interact with each other in three different cases: With no barriers, one barrier and two barriers. We did some kind of experiment, and then drew our observations and made conclusions.
Firstly, we took a tub and filled it halfway through with water and placed it on the table. We used hard clay as the barrier and our fingers for creating a wave.
When we tested how they interact with each other with no barriers, we found out that the waves continue going to their path even though they meet in the middle. They don’t go back and they don’t even go to the side- they continue their movement, however with just another strength- they will become stronger than they were before meeting each other.

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After this, we put a barrier in the tub filled it with water, and tried to see what happens when waves meet in the middle. When the waves bumped into the barrier they have changed their directions and continued their movement in a new direction. I thought this was normal, because waves can’t go on the barrier or go IN the barrier.

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Using two barriers on the side of the tub (in a closed manner), and started creating a wave from another edge, we figured out that waves can’t go in the space between the two barriers, waves can only go around it. In another case, if we create a wave inside the barriers but leave a small opening, one part of the waves will go back, and another will pass through a small opening and start spreading around it.
Mrs. M gave us an example about the marine full of boats being closed in an area. When waves are being disturbed, they can’t go in the marine because it is closed- so the boats are safe.

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What happens when waves hit a surface?
This was another interesting experiment which I thought was simple and obvious that when waves hit a surface, they travel back, I thought it would be like that in the beginning, however, different kinds of balls travel in different ways. For example, if I hit a type of ball (metallic marble) toward a wall, it stays there because it was too heavy to go back. Comparing a metallic marble with a golf ball, there was a big difference. A golf ball immediately goes back when its’ hit. In my opinion, it depends on how hard you hit a ball. If you hit it hard, then the disturbance of a wave goes back really fast. If you hit the ball lightly, it stays next to the wall. My partner and I decided to hit each ball in a uniform speed way, and most of them didn’t travel back, however a smaller number of them traveled back.
As you can see, when a ball or in our case wave hits a surface, it travels back by the same angle in which it hits it.




In conclusion, we were given the assignment to connect these discovery activities with the section we had to read. The section talks a lot about what we did in class, this means that it was easy for me to connect it to the discovery activities.
In the first discovery activity, where I had to answer: How do waves interact with each other with no barriers, one barrier and two barriers? Having one starting wave begin from an edge, and another from a totally different side. When they meet in the middle they will continue their movement in the same direction but with greater force going up and down. This is called a positive interference, or a constructive interference, and it is occurring because the amplitude of our waves are adding to each other and are becoming bigger.
With one or two barriers, the waves will certainly reflect from the barrier in the angle which is equal to the angle of incidence. This is occurring because of a reflection, also, when we have two barriers with a small opening between them (picture 6) we saw that some of the waves were reflected. But also some parts of it passed through the opening and started spreading through the water, this is called a diffraction.


In the second activity, we had to conclude: What happens when waves hit a surface?
When a wave hits a surface by some angle (called an incidence angle) it goes back, in a changing direction. This other angle is called a reflection angle. These two angles are always equal. The surface where the balls were hit is called a reflection surface.