​Here the wave phenomenon shown is the reflection of the wave when it reaches the boundary of the medium. What occurs here is that the speed of the wave stays constant, while the amplitude is dampened after the reflection. Any time a wave encounters a boundary, some of the wave is reflected back, and the pulse move in the opposite direction. Wave inversion occurs due to the fact that rigid waves always invert and that energy is transferred in the opposite direction and the wave is flipped.
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Here in this example of rotational motion, we have a wakeboarder doing a flip in the air. The physics behind this wonderful trick I have been mastering the past couple years is quite simple. The most basic is that the motion of the boarder is horizontal to the boats in terms of the relative position from the boat. The boarder is moving at a speed around 20mph and uses the rope as a tension force. By turning the board more perpendicular to the motion of the boat, the boarder can move across the wake. This is because the way the board is designed, which ever way the board is facing the person will move more in that intended direction. By using these boarding mechanics, the boarder can move from one side of the wake to the other while also achieving air time by using the wave of the wake. The constant velocity of the boat, the tension force of the rope, and the force generated by the board and the water allows for this flip to occur. By pumping the board as it rides up the wake rapidly allows for a greater applied force up on the board which results in air time. The complex movement of the body while in the air allows for the rotation about the axis of rotation; that being the rope. Throwing the body backward while flying into the air applies a torque about the center of rotation. With an uneven distribution of mass, and the correct form, the boarder can land the jump after flipping. This is due to an oscillation in rotation because of the nature of the flip. Kinetic energy is built up as the boarder rides into the wave of the wake, which allows the boarder enough time and torque in the air to complete a flip. Momentum is used in this case where the boarder builds up enough momentum to stay moving while in the air completing the flip and ending up on the other side of the wake. Finally, there is a centripetal force that is applied toward the boarder, since the board is attached to the feet and is of significant mass. As the flip occurs, the centripetal acceleration points toward the axis of rotation, that being the rope.
In the image above, it is evident that construction was done to lower the risk of accidents and make it safer. This especially applies to driving in the winter time. The reason for this is because if drivers take the turn at too high of a speed, they may end up sliding or losing traction. Which will potentially cause a dangerous accident. The scientific basis for why this occurs is mainly centripetal force. If the radius of a turn is small, as shown in the image to the left with the red arch, centripetal force must be greater to keep the car on course with the turn. In a scenario during the winter where there may be ice present, it would be especially dangerous because the necessary centripetal force to take the turn can not be generated in instances of ice where friction is less. This all relates back to the equation below and how different variables manipulate the situation relating to centripetal force. Assuming mass and velocity stay the same, if the radius increases, then the centripetal force generated during the turn is smaller, meaning it is more safe as seen in the green arch in the picture above to the right.
After taking my first AP Physics 1 Test, I feel that this class is manageable as long as I get my work done on time and completed in a timely manner. I feel that I have struggled with this so far because I have never had this difficult of a work load in general and as a specific class. I think that even though I probably got around an 80 on that test, I think that I did better than what I was expecting to do on that test. The biggest reason for this is because the work on pivot, mastering physics, and module assignments are in my opinion slightly more difficult than what I saw on the test. With the exception of a few questions of course that I feel I could have been prepared better for. Obviously however this is an AP class, so the traditional style of teaching and the customary speed in which the classes are taught is currently suspended. Ways that I studied was to use Khan Academy and also the assignments like the dynamic study modules and other assignments we had assigned prior to and leading up to the test. This is a positive because even though the work load in this class is very difficult for me, having that amount of work assigned to complete and relating to the material on the test helped me prepare for the test as if it was studying.
How do you feel about the class so far?
I feel that the class is at a good pace for me so far. What I like most is that so far it is relatively similar to the material I saw in freshman physics. What I dislike the most is that the majority of questions I ask my classmates go unanswered, this means I in a way have to focus a lot harder to not get behind and ask questions; act like I know everything that's going on when I really don't. Do you think you are in the right place? I do believe that this class is the right place for me because I feel that after the pre-test taken in the second week of the class to give an idea of how prepared I am for the class, and feeling very confident, I would get off to a good start this year. Starting off understanding the topics and good grades makes it a lot easier for me to continue that streak and work harder. Pretty much if I do well this first quarter this is going to be a lot easier to keep good grades. What are you concerned about moving forward and what are you excited about? What I am most concerned about is the workload and being behind in understanding what is going on like what is happening for a lab or what specifically needs to be turned in. I am most excited to learn my second favorite subject in school. |
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