Grace+Carroll+9-26-08

On Friday, September 26, 2008 I participated in Mr. Manning’s fourth period physics class. The class started out like any other class; the students took out the materials they needed for the day, chatted with their friends, and eventually focused their attention on Mr. Manning. On this day, (along with every other day) he presented the students with a daily question, which was written on the board. Friday’s daily question asked what the sum of the forces were. The forces that were displayed showed a total of six people balancing on one rope. Three people on the left side, (Team Aristotle) weighed 150 N, (Newtons) 125 N, and 165 N. Three people on the right side, (Team Galileo) weighed 160 N, 115 N, and 155 N. The sum of the forces was 10 N, and the forces were not balanced on the rope because there were different totals on each side. For example, Team Aristotle weighed a total of 440 N, while Team Galileo weighed a total of 430 N. After completing the daily question, we moved on to our next activity. The day before, the students had worked on a lab involving unbalanced force. The teacher explained how unbalanced force related to the daily question, and if it is applied to an object, the object will move. After recapping yesterday’s lesson, it was time to move on to Auto Control! We learned about this in quite an interesting way, through a “rap.” The rap, which I learned was created by Manheim Township Physics teachers, described what happened as one drove on a highway and went through various stages of speeding up and slowing down. The point of this rap wasn’t to entertain our minds with songs about driving, but to describe how it related to net force. I learned that net force is the amount of force an object feels, and there are three factors that contribute to net force equaling zero. In order for net force to equal zero, an automobile has to be moving at a constant speed, moving in a continuous straight line, or come to a complete stop. This relates to unbalanced force because if an automobile receives an unbalanced force, it will accelerate. After learning about the main concept of net force, it was time to answer some questions! Before answering these questions, we learned some more basic concepts. The reason a car moves in a horizontal direction, is because of two forces that are pulling it. One force is the force that comes from the motor, which pulls the car forward. The other force comes from the engine, the wheels, and in between the tires and the road. This force is called friction, and it causes a car to slow down by slowly pushing the car in a backwards direction. After learning this, we had to decipher a few problems and decide which was stronger; the magnitude of the motor force (M) or the magnitude of the friction force (F). If the magnitude of the friction force equaled the magnitude of the motor force, we would simply but an “E”. If one is stopped at a stop light, and then presses the gas pedal to accelerate his car from zero to sixty miles an hour, the force from the motor would be stronger. This is because when a car speeds up, the motor is doing most of the work. If one is driving around a corner and sees cars stopped ahead of him, he will ease off the gas pedal to slow down so he doesn’t ram into the cars ahead of him. In this scenario, the friction force would be stronger, because friction allows the driver to slow down, and he is also letting up on the motor in order to slow down. When one drives at a constant speed, the friction force and the motor force would be equal. An example of driving at a constant speed would be driving on a straight, even road at 55 miles per hour. Once we were done learning about unbalanced forces, auto control, and net force, I thought we were done for the day. But there was one more part of this physics class that I had not yet experienced, a lab. Unfortunately, we did not get to complete the whole lab, (the actual experimenting) because there was not enough time in the period, but we did make predictions. Mr. Manning used spring scales and weights and then asked us questions based on the weights and scales. On the four different scales, there were two weights on two scales and three weights on the other two scales. In total, the two or the three weights all added up to weigh 10 N. Our first prediction was figuring out how much each weight weighed. I guessed that the scales that contained two weights each weighed 5 N per weight. On Scale A, the two weights were piled on top of one another, but on scale B, one weight was on one side of the scale while the other weight was on the complete other side. For the scales that contained three weights, I predicted that two of the weights weighed three and a half pounds, while the other weight weighed exactly three pounds. On Scale C, the three weights were spread out evenly, but on Scale D, the weights were piled on top of one another. After predicting the possible weights of the scales, we made two more predictions. If we moved the hanging weights to the right or to the left, we had to predict what would be the same and what would be different about the scale readings. I predicted that the scale readings would differ by two to three Newtons, but that the scales would probably weigh the same once the weight would be moved to the right or to the left side. I predicted this because the same amount of weight would be distributed to either side. We made our third prediction based on a diagram. The diagram showed a stick figure walking across a platform in between two scales, (scale one and scale two). Scale number one, which was on the left side weighed 1,200 pounds where as scale number two, on the right, weighed 0 pounds. We had to predict what would happen to the two different scales as the stick figure walked from scale one to scale two. I predicted that scale one’s weight would decrease because he would be walking away from it, but scale two’s weight would increase because he walks in that direction; more weight would be distributed to that side.

After learning about forces, auto control, singing a song, making predictions, and witnessing live demonstrations involving spring scales and weights, the period was over. I was disappointed to leave the class, but learned many new things that I had not known before. I learned the differences between the forces that allow my car to speed up and slow down, as well as what causes net force to equal zero. If given the chance to observe and report on this class again, I definitely would. Not only was it a great experience interacting with other students, but I was challenged. Look out for next week’s article, as I observe my second period trig class!