I chose to answer the question which pendulum will come to rest more quickly-a lighter pendulum or heavier pendulum?
As an educator, I believe that before we teach our students a concept we first must develop an understanding to the concept. According to Buxton & Provenzo, Jr. (2007), educators need to understand and develop the skill of guiding students to an understanding of science concepts without prematurely telling them what sense they should make out of inquiry experience. I accomplished this task by exploring the different site available to me that was listed on Walden’s University web site. I also explored Newton’s Cradle and the principle related to it. As I played with the Cradle I experimented with it and with my niece’s ages 14 and 16. I asked them if they had ever played with a pendulum or a cradle (not a baby cradle). I described to them the Law of Conservation of Momentum in a closed system like a cradle, the momentum in a given direction is constant, that if I take a ball at one end of the cradle and let it go the ball at the other end will react because of the force that was pushed against it and it will bounce, the momentum of the ball hitting the balls in the middle will continue until there is no more force. While the balls in the middle will stay stationary, as we played with the cradle I asked them what will happen if I used two balls instead of on. Their reply was that the ball at the other end will react to the force and move. They were amazed when they observed that the instead of just one ball at the other end move, there were two. We played around with this for another twenty minutes. I explained that since the ball at one end had the same mass as the other ball at the other end, the result will be the same even if we had a hundred balls as long as the balls were the same mass, same size and there was no deviation.
I started with this demonstration of a pendulum to show my nieces how one works. I then asked them if they could tell me what could affect the movement of pendulum. I discuss them about what gravity is, which they already knew, what momentum is, what mass and velocity is. We made a pendulum using a string a ball and a pencil. It looked pretty rough but I was amazed that it worked. I discovered along with my nieces how to make a pendulum that worked through trial and error. The first couple that we had made didn’t do the experiment justice. As I research how to improve the engineering of the pendulum I discovered a great site, http://phet.colorado.edu/en/simulation/pendulum-lab that allowed us to experiment what factors could affect the movement of a pendulum. This is a great site to explore with all of your students. I haven’t taught my students this concept yet, but when I do I believe that I will be better prepared than I was when I introduced this to my nieces. My goal when teaching this lesson will include: the students will be able to answer and describe what the Law of Conservation is? What is deviation? What is momentum? What affects the momentum of a pendulum? What is mass? They will also be able to understand the concept. I will allow them to make the mistakes that I made, and encourage them to refine and optimize their designs. They will develop new understanding, and gain insight into and an appreciation for science and the technology world.
Out of curiosity, how will you explain to your class which pendulum lasted longer and why?
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As I introduce the pendulum we will discuss what could effect the swinging of the ball. Gravity, length of string, mass of the ball, degree of the angle that we start with when when we start the ball in motion. We will experiment changing each variable one at a time. I found that the shorter string with the same mass and force of gravity will stop before a longer string, for it will not have the momentum as the ball on the longer string.
ReplyDeleteThis was such a thoughtout great lab. I am really impressed how you took it further and did it with your nieces. I was just wondering if you only did this experiement with your nieces or did you have a chance to do it with your students, and if you could estimate how long it took you? I was just curious because I only have a 40 minute period with my students.
ReplyDeleteI was able to do a shorten version with my students because they had already seen how a Newton's Cradle worked. I was also able to go into the computer lab where each of my students were able to complete the experiment on the following site: http://phet.colorado.edu/en/simulation/pendulum-lab This allowed me to teach this concept in my 45 min. class period. Though we did a follow up the next day.
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