Unit 5 Blog Post

We began the unit by learning about rotational and tangential velocity. Rotational Velocity is the time it takes for 1 rotation, or the number of revolutions in a certain time X period. Tangential Velocity is the distance converted in a certain amount of time. If an object is on the outside than it has a tangential speed but the inside and the outside have the same rotational speed. We also learned that one has an advantage if they are on the inside track because they have less distance to run. We also learned that when you roll a cup the reason the cup curves is because the wider end and the smaller end have the same rotational speed, however the bigger part of the cup has a faster tangential speed. This also has to do with the design of the train wheel. A train wheel is smaller on the outside and bigger in the inside. This is because when the train shifts to the left the larger diameter of the wheels are on the left track and the smaller diameter is on the right track. Therefore, the smaller diameter is slower tangentially and the larger ones are faster. Therefore the train will curve to the left keeping it on the track. We then applied these concepts to real life situations. For instance, in roller derby the purpose of the whip is to gain tangential speed. The reason the leg is more effective is because it has a longer diameter, which means it has a faster tangential speed, because it is further away from the axis. Our next unit was about rotational inertia. Inertia is the property of an object to resist changes in motion. If there is more mass than there is more inertia, because more mass makes an object harder to stop and start. Rotational inertia is how much an object is willing to spin. And it is the property of an object to resist changes in spin. If there is lots of rotational inertia than the object is hard to spin, and where there is a small amount of rotational inertia it is easy to spin. Rotational inertia is also affected by where the mass is located. If it is further from the axis then it is harder to spin because there is more rotational inertia. If it is closer to the axis then it is easier to spin because there is a small amount of rotational inertia. Why do runners bend their legs? Lowering rotational inertia=easier to spin. And in terms with an ice skater when the arms are away from the body there is more rotational inertia. Conservation of angular momentum is (total angular momentum) before=(total angular momentum) after: p=mv Angular momentum is affected by rotational inertia and rotational velocity. We then learned about torques. We began this lesson with the question where is the best place to put a doorstop: in the middle of the door or at the edge closets to the handle? The answer is at the edge closest to the handle. This has to do the torques. A torque is what causes something to rotate. Toque=(force)(lever arm) a lever arm is the distance from axis rotation. If you want something to rotate you apply a large force to it. You can do that by either apply a large force or a large distance. Therefore, just because you have a large torque doesn’t mean you have a large force. A center of mass- the average position of all mass. The only way you fall over is if there is a lever arm→ only way there is a lever arm is if the center of gravity is not above the base of support. *On a balance beam the center of gravity is as low as possible because it will be harder to shift that out from underneath the base of support. Counterclockwise torque=clockwise torque. Lastly we learned about centripetal force and centrifugal force. When you are riding in a car and it makes a turn you feel like you are forced to the side of the car. This has to do with the properties of inertia, which is that an object continues to do what it is already doing. Centripetal force is the center seeking force, which keeps you going into a curve. Centrifugal force – is the center fleeing force NOT REAL. There is no actually force pushing you outward. We then went over how the washing machine spins to get rid of excess water. When it spins water comes out however it is not being forced out. Once it starts to spin you give it velocity, when the water starts moving no centripetal force causes it to stay in its path. My effort towards class is pretty consistent and I feel that I am a persistent participant. I also go in early when I feel that it is necessary. And my effort is reflected in-group work especially, which is a time that I am fully involved with the activities. I do my homework almost every night. The only time I didn’t was when I was not clear on the assignment. I always try to find real life videos and then explain them instead of having a video teach you the lesson, I feel as though this reflects that I am dedicated to having an engaging blog. By going in early and asking questions in class I feel that I have strong communication. And my creativity was reflected when making the podcast, and how my partners and me would use real life examples and then further discuss them. My goal for the next unit is to make sure I study before each quiz and go in early to be tested on my knowledge of that particular unit. The connections I make with everyday life is usually seen in sports. Like a torque is what makes people do flips off of the diving board and rotational inertia is what causes an ice skaters speed to increase when she pulls her hands close to her body. A torque also has to do with