Impulse Lab Write Up K leigh Olsen 6th hour March 13th, 2014
! Over the course of the week my group composed of Tyler, Valerie, Isaac and my self, were asked to design an experiment to find out if different shoes exert a different force when walking and/or jumping. Some industries that would be interested in knowing if the bottom of the shoes exerts a different force would be shoe makers. They would want to know how they can improve their product and have less impact on certain parts of the foot. As well as a way to see the wearing down of the shoe itself. Also floor layers might want to know what kind of shoes to wear while installing a floor. When floor layers lay a wood floor, they dry lay everything down before the permeant glue. If their pieces are stuck together because of all the force that has been exerted on them then it will be harder to get the job done. The company overall will be spending time taking apart the floor and having to glue it down because of a simple mistake. We believe from the lab that we conducted, that the bottom of the shoe does not make an impact on the force that the shoe exerts. My group and I gave a lot of thought in the beginning as to if the bottom of the shoes will effect the force and what a clear hypotheses should be.! Our original hypotheses was that If the bottom of the shoe was flat with no impurities in the surface then it would exert the greatest amount of force on the force plate because there would be direct contact with the whole shoe and the force plate. In order to figure out if our hypothesis was correct we had to perform an experiment that we designed. For our experiment we decided to record the variable of the average force that was exerted on the force plate. We decided to record this variable because we thought that it was most important to record the average rather than the maximum force or the impulse. Maximum force could be dependent on the force that Tyler steeped on
the plate at just one particular time, we concluded that this was not accurate.impulse was the other choice, impulse is dependent of the force multiplied by the time interval. We were not interested in looking at any time variable, just force, therefor this is why impulse was not measured.! Our group member Tyler preformed all three trials with walking and jumping for the cleats, running shoes and the heavy weight boots. We performed three trials because we wanted accurate results. We decided to perform a controlled experiment. A controlled experiment is when you are able to manipulate what is changed. The independent variables is a variable that does not depend on another. The independent variables that were present were mass, shoe type, shoe weight and the lab station, the only variable that we changed was the shoes which change the weight as well. The dependent variable is a variable that depends on other factors. The dependent variable was the force exerted on the force plate when changing the shoes. A confounding variable is a variable that is hidden but correlates with the dependent and independent variables. Some confounding variables were the lab station that was used and the day that we performed the experiment. Even though these things are so small they still can directly effect the independent and dependent variables. We used the same person because we needed the mass to stay consistent. Tyler had a mass of 68 kg which is equivalent to a weight of 666N. The mass of the shoes were all different as well, the boots were the heaviest. Next were the running shoes and then the soccer cleats. This proof is present in our data because the average forces for each shoe corresponds with their weight. The boots exerted the most force next the running shoes and then the
soccer cleats.when collecting this data we used a very clear procedure to be sure that no mistakes were made.! To collect the data we used a pretty simple procedure. Our group member Tyler was asked to bring in three different types of shoes. He chose to bring boots, Nike running shoes and soccer cleats. When Mrs. Yager gave us time to do the lab we got right to work. We made a data sheet on a lined piece of paper, the front was for walking results and the back was for jumping results. On each side we made four rows with five columns. On the top we listed trial numbers, trial 1, trial 2, trial 3 and average. On the left side we listed boots, cleats and Nike running shoes. This is how we set up our data collection sheet then moved on to the experiment.! To start the experiment we first opened up the Logger Pro software on the Mac computers. It opened up to a graph with functions on top and on the left. We determined that Isaac would be the person to click the buttons. We wanted to have one person so the results stayed accurate. To start the graph he pressed the square green button at the top that looked like a play button on a television remote. After he pressed the button we had Tyler walk at a very normal pace across the force plate starting from about three feet away from the plate. After Isaac had pressed the stop button which was a red square with a smaller white square in the middle then a graph appeared on the screen. On the left of the graph was the force in Newtons and on the bottom was the time in seconds. He then highlighted the portion of the graph that first started to show force because of the incline shown. Isaac highlighted it to the point where the line was done declining. He highlighted the portion by clicking and dragging to the points that were wanted. We then needed the information from this trial. To obtain it, Isaac clicked the
statistics button at the top of the screen. We knew to measure the spike in the graph because that meant where Tyler had walked across the plate. When the statistics showed up, it listed the information about the portion of the graph that Isaac had selected. As stated before we decided to record the average force exerted on the plate because it telling the average or mean amount of force that was exerted. After we recored the amount on out lined piece of paper we had to reset the graph. We did this by zeroing out the plate using the zero function on the top tool bar. We repeated theses steps for all walking trials. For the jumping results we did a little different procedure.! In order to get accurate results for jumping we had to first zero out the force plate once Tyler was standing on the plate. When this step was completed Tyler then crouched down with his hands on his hips. We then had Isaac press the start button at the top of the screen. Once Tyler jumped Isaac pressed the stop button, from there we followed the exact same procedure as we did with the walking results. This was the end of the lab and we apple quit the Logger Pro software, now the data needed to be analyzed.! When the whole experiment was completed it was time to look at the results. What we found was very different from our hypothesis that we had made at the beginning of the experiment. We thought that If the bottom of the shoe was flat with no impurities in the surface, then it would exert the greatest amount of force on the force plate because there would be direct contact with the whole shoe and the force plate. We then came to conclusion, that was not the case. We concluded that all of the forces were equivalent to Tyler s mass. The reason why the numbers are not exactly the same is because the mass of the shoes. When walking, the boots average of the average
forces was 526.3N, for cleats it was 465.7N and 743.3 for the Nike running shoes. The boots had the highest force because they were the heaviest of the three shoes. Newtons second Law is very supportive in this case. Newtons law states that for every action there is an equal and opposite reaction. In this case the action was Tyler pushing down on the Force plate and the reaction was the force plate pushing up on Tyler. Although the force was not different, the counterclaim is that pressure what makes a force seam greater on the bottom of the shoe. Pressure is defined as force divided by area. If we were measuring pressure on areas of the force plate the soccer cleats would be exert the most because of the spikes. The Nike running shoes would be next and then the boots because the running shoes had more impurities in the surface. We were not measuring pressure so this thought has not yet been proven by my group. Another problem could have been human error with the interpretation of the graph and the speed of walking. Errors like these tend to happen in self lead labs. How ever there is many things that we did to strengthen our experiment.! Every experiment has its strengths and weaknesses. Some of the strengths in our experiments was that we constantly used the same lab station. This is such a small variable but the speeds of the computers are all different. Also the force plates are all not exactly the same. We thought that it was important to keep the person who reads the graphs and pushes the button constant. People can have different interpretations of the graph and judge distances differently. We kept the walker and jumper the same because if we used a person other than Tyler, the results would not be consistent and very unreliable. There were a few weaknesses to our experiment, one was that we should have completed all of the trials in one day. The mass of Tyler could have
changed because of the activities he engaged in and the cloths that he wore. Also when all of the experiment was not done in the same day the computers grew older because they were running for longer, ultimately aging. A question that I still have is if Tyler were to jump but extend his legs in the air to make a bigger impact on the force plate, if it would actually make a greater impact. I think that a great new study would be to maybe calculate the pressure of the different shoes. If we would have calculated pressure than the lab results would have been much different. I think that knowing the pressure could further determined different results if we would have had the right equipment.! In conclusion, this lab was very successful. We talked about the procedure, variables, materials and how we collected the data. My group and I figured out that the force did not depend on the type of shoe. The weight of the shoe was the determining factor of what force was exerted on the force plate. Since we performed a controlled experiment the only thing that the data was dependent on was the over all mass of Tyler plus the shoes that he was wearing. Now knowing this, we concluded that a better thing to extract from this lab wold have been the pressure of each shoes exerted on the force plate.
Data Collection ** I talked to you in class about before you told us to attach our original data, I had already made a table and my original data was at the bottom of my trash can.this is the exact data.** Walking Results (measured in Newtons) Trail number Trial 1 Trial 2 Trial 3 Average Boots 516.3 547 515.7 526.3 Cleats 481 481 435.2 465.7 Nike Running shoes 474.1 481.3 464.4 473.3 Jumping Results (measured in Newtons) Trail number Trial 1 Trial 2 Trial 3 Average Boots 684.1 584.8 742.9 670.6 Cleats 464 410.8 458.6 444.4 Nike Running shoes 325.1 435.9 588 449.6