Science Interim Assessment Task 9th Grade Projectile Motion The task below forms the main focus of the unit on Projectiles. Students explored some of the properties of projectiles using different types of balls on the first day of the unit. On day 2 students were introduced to the river gorge scenario, where they brainstorm ideas about how they could solve the problem. We decided to use catapults as a way to approach the problem. Students were provided with a checklist to guide their progress as well as a description of the required sections of the project. Students were required to test one of the two variables changing arm length or angles to see how range and initial velocity are affected. Concepts were developed during circle discussions and research from articles provided. A graphic organizer was provided to assist with recording research summaries and bibliographic information. Research summaries were organized into a logical and coherent two-page paper. Students practice using protractors to measure angles by making scale diagrams which they applied while collecting data. They were also required to apply skills and concepts from previous lessons on measurement, kinematics and force. Unit Project Problem Instructions Read the scenario below and then answer the questions below. River Gorge Scenario You are 6 days into a 2 week hiking trip with a group of friends near the Royal Gorge in Colorado. As you walk along the trail you notice how steep the cliff walls are that drop down into the Gorge. You and your friends are trying to decide how deep the gorge is (about 365 m) when you hear cries for help coming from across the Gorge. You notice a group of hikers who appear to be stranded across the river. They decided to cross the Gorge on a rickety old bridge that gave way just as their last group member finished crossing. The hikers indicate to you that they have been stranded for 4 days now without any food or water. They are dehydrated and weak, you must do something to help them! You all try your cell phones but you have no signal. Two of your group members volunteer to hike back out of the wilderness to alert the authorities, but you know that you must do something to help the hikers until someone can come rescue them. Questions: But how will you get food and water across the Gorge to them? The cliff walls are too steep to climb down. Can you think of anyway to help them? Modified from original resources on this website http://www.ncsec.org/cadre2/team29_2/catapult/catapult_module.html Science Project Checklist Use the following checklist to rate your progress for the project. Have you: Selected a Question for your experiment Created a topic web Used topic web as well as research summary to create a main research question and sub-questions Completed research on your topic from the resources provided Cited your source for all information collected on note taking sheets Organized you literature review into a 2 page paper Literature review graded by you and your peer Develop a design plan and build your model Created hypothesis for your experiment Identified independent and dependent variables Identified controls Organized materials that you will need to collect data Prepare procedure for collecting data Collected data and organize them into tables Create graph Discuss your results Conclusions tied to research, hypothesis and data Recommendations for further research Problems and mistakes Projectile Motion The Catapult Lab Objective: To apply the laws of Physics and the equations for projectile motion to design a catapult that can accurately launch a marshmallow and hit a designated target. Requirements and Design Rules: 1) In this lab you will be building marshmallow catapults. 2) Your catapult will need to be able to launch a marshmallow in the range of 3-6 m. 3) Your catapult must be able to launch a marshmallow (large variety – approximately 4 cm X 4cm X 4 cm) at any angle between 0 and 90 degrees. The Look All catapults should be composed of scrap materials found that you provide I will provide the marshmallows. The appearance of the catapult will not be judged, but you should pay careful attention to design elements that affect the ability of your catapult to adjust to new distances. There are several design ideas provided on the attached sheet. You may use one of these designs or adapt one to guide your catapult design. Product to be submitted You need turn in a report You will have 2 class periods to design and build the catapult (keep this in mind so that you can work at home if necessary). Format for Report You will be graded on the following items: 1) Background Research 2) Design Plan 3) Data Collection 4) Data Analysis 5) Conclusion 6) Organization and presentation of report Select one of the following questions • How does changing the angle affect the initial velocity and range of the projectile? • How does changing the length of the arm affect the initial velocity and range of the projectile? Your background research must include but not limited to the following: Information about the history of catapults and how they have been used o Projectile motions concepts o Information about River Gorge o Energy o Force Use the note taking sheets to collect information about each concept in your web. Organize your research into a logical and coherent 2-page paper. Include your references. Your Design Plan Must Include: 1) A list of materials to be used (should be bulleted) 2) A diagram of your catapult. 3) A description of how you will build the catapult 4) The diagram should have all dimensions labeled (including units) and should be neatly drawn. 5) Your diagram should be drawn on plain white paper and should fill most of a single page. Resources: http://www.stormthecastle.com/catapult/how-to-build-a-catapult.htm http://www.knightforhire.com/catapult.htm http://hubpages.com/hub/thejockspot_how_to_build_a_catapult Use the following links to find out about this gorge. Make a list of any ideas to get that could help you solve the problem http://www.royalgorgebridge.com/ http://www.royalgorgebridge.com/RGBP_Video/video.html Procedure for Data Collection should include a description of: Appropriate hypothesis related to selected question What are the variables needed to describe projectile motion? What data will you collect from your physical experiment? How will you collect the data from your experiment? Your Collection and Data Analysis may include: 1) Data table that includes time of flight(s), distance flown in horizontal direction, angle of launch, or length of arm. You must test at least 3 different angles using 2 replicate trials for each angle. ( Your table could look like this) Independent Time Horizontal variable 1 distance 1 Time 2 Horizontal Average Average distance 2 time Horizontal Distance Initial velocity Independent Time variable Distance Initial velocity 1 Time Distance Initial Average velocity 2 initial velocity Data Analysis 1. A value for the average initial velocity of the marshmallow and an explanation of how initial velocity of the marshmallow was determined. (Refer to class discussion regarding determination of initial velocity.) 2. a. How did changing the angle affect the characteristics of your trajectory? The initial velocity? OR b. How did changing the length of the arm affect the characteristics of your trajectory? The initial velocity? 3. What are some limitations of your physical model? 4. What are the sources of error for your experiment? Conclusion: Your conclusion should include an overview of your findings and describe any sources of error that might be present. Give some examples of real life projectiles whose landing spots must be carefully predicted. Explain the best situation for solving the river Gauge problem. Organization and Presentation: 1) Report should be neatly typed or written and sections should be well-marked. 2) Mistakes must be either erased or corrected with white out. 3) All answers are presented in complete sentences (excluding the list of materials, which may be bulleted). Rubric for Catapult Laboratory Report Outcomes Below Meets Above Standards Standards Standards Statement of Objective: States why the student is doing the 0 2-3 4-5 0 2-3 4-5 0 1-2 3-4 0-1 2-3 4-5 0 1-2 3-4 Accuracy: Projectile hit target on testing day. 0 1 2 Organization and presentation: Report is neatly typed or written, 0 1 2 0 2-3 4-5 0 2-3 4-5 investigation and what the goals are. Should be clear and concise. Clearly states the question and sub-questions. Hypothesis that is being investigated. Independent and dependent variables Design Plan: Complete description of the catapult and diagram with all parts labeled and clearly drawn. Description of steps used to build the catapult. Actual; model of catapult Data: All steps for collecting data described. All data taken should be listed in this section. All data must have units and data tables should be clearly labeled. Must include: time of flight, distance in x-direction, angle of launch and initial velocity. Data Analysis: Correct equations have been used, calculations are correct and appropriate units are used. See laboratory sheet for additional requirements. Conclusion: Results are summarized and the hypothesis addressed. Significant sources of error and suggestions for improvements are addressed. sections have been well marked, mistakes are either erased or white-out. Manipulation and measurement: Follow Safety instructions carefully, setup and use carefully and competently laboratory apparatus. Background research Information summarized on note-taking sheets. Essay organized in logical order with appropriate grammar. Bibliographic information on page attached. Total: points Physics Note Taking Sheets Select topics from your topic web. Examples speed, force, catapult, range, angles Define each term and explain how it is related to projectiles Use the note taking sheets to record your information Information must be written in your own word and source recorded to receive credit Book ______________________________________________________________ ___________ Author name or Editor name Date ___________________________________________________________________________ Title of the book ___________________________________ Location _____________________________________ Publisher What I learned from this source Book ______________________________________________________________ ___________ Author name or Editor name Date ___________________________________________________________________________ Title of the book ___________________________________ Location _____________________________________ Publisher What I learned from this source (use back of sheet for additional space): Internet Article (not based on a print source) ______________________________________________________ ____________________ Author name Date ___________________________________________________________________________ Title of full work Retrieved on ___________ From _______________ Web site ________________________ Date Name/Sponsor URL * Where possible print a copy of the article with URL What I learned from this source Internet Article (not based on a print source) ______________________________________________________ ____________________ Author name Date ___________________________________________________________________________ Title of full work Retrieved on ___________ From _______________ Web site ________________________ Date Name/Sponsor URL * Where possible print a copy of the article with URL What I learned from this source Sample IA ----9th Grade Student work Physics Catapult Lab Essay Background Research For this lab, we had to make a catapult and change either the angle or length of the catapult’s arm to observe the effect on the projectile’s velocity, time to launch and land, and the distance the projectile traveled. In this case the projectile was a marshmallow. What is a projectile? Well a projectile is any object that once dropped, gravity is the only force acting on it 1. Based on what we had to do in this lab I questioned how changing the catapult’s arm length affects the initial velocity and how it affects the range of the projectile. Because a hypothesis is an educated guess that is based on knowledge, I couldn’t form my hypothesis until I did a little background research. From this research, I discovered the definition of a projectile as stated above. I also found that the word “catapult” is used to describe a machine that hurls or launches a projectile, for example a sling shot or cannon.2 Objects that are projectiles not only move vertically, but horizontally. As an object move horizontally, the object continues to move downward because gravity is the only force acting on it3. To help with the design of my catapult I found that there are three major types of ancient catapults: the Ballista, Onsager, and the Trebuchet (which is the oldest catapult and was invented by the Chinese). The Ballista was invented by the Greeks and the Romans. Another type of catapult is the Shagouf, which is a long pole balanced in the middle of two poles, with a weight on one end and a rope attached to the other end with a bucket tied to it kind of like a see-saw4. Catapults started being used for hunting by flinging small stones, then to defend castles. Overtime, as the castles grew bigger the catapults got larger as well, then they were used during wars. Catapults that were built with wooden arms allowed the catapult to hurl stronger, sharper objects, and increased the speed of the object. The mightiest catapults could hurl an object over three hundred pounds5. 1 www.physicsclassroom.com/class/vectors/u3l2d.htm www. catapults.info/ 3 www.pyhsicsclassroom.com/class/vectors/u312d.htm 4 www. catapults.info/ 5 Catapults History, www.buzzle.com 2 Also, the longer it takes the catapult to rise, the less velocity the object or projectile moves at6. I also discovered that the longer the catapult arm is, the higher the projectile’s velocityis7. The best angle to launch a projectile is a 45-degree angle because the projectile will move halfway between a horizontal and vertical motion. A 45 degree angle is the best angle because if a projectile is launched a 90 degree and it doesn’t move horizontally just vertically, a 45 degree angle moves both horizontally and vertically 8. I also found that Isaac Newton’s statement that an object in motion tends to stay in motion, also known as inertia. Inertia plays an important part in projectile motion because it explains why an object in moves without a source of propulsion9. Also a vector quantity is something that has both magnitude and direction. A good example is velocity, which has both speed and direction. This is a good example because the definition of velocity is a speed in a specific direction. After researching, I was ready to form my hypothesis, which states that the longer the arm is in length, the less time it takes the catapult arm to rise, the higher the projectile’s velocity and the farther its range. Design Plan With my hypothesis formed, I was ready to build. My materials were: ○ 20 Popsicle Sticks ○ Tape ○ A Pen/ Pencil ○ A Rubber band ○ Scissors To build my actual Catapult we had to: 1. First we had to make the structure, which needed 12 popsicle sticks. To do this I taped two sticks together. (Repeat this 6 times.) 2. To finish the structure or base of the catapult, I then take the popsicle sticks that I had taped together and then taped them in the form of a pyramid. 3. The next step would be to make the catapult arm, which takes about another 5or 7 popsicle sticks taped together then tape this into one of the bottom corners of the pyramid. 4. The last step would be to make the paper cups, which I use, a square pattern, and tape them on to the catapult arm at different lengths. The cups should be at least 2 centimeters apart. 6 www.physicsclassroom.com/class/vectors/u3l2d.hlm http://tuhsphysics.ttsd.k12.or.us/Research/IB05/AsaiGrafPete/index.htm#conc 8 Physics A First Course by Tom HSU,PH.D, 2008 9 www.wisegeek.com/what-is-projectile-motion.htm 7 I decided that in order to make my experiment more efficient, my partner and I would put the cups at different lengths of the catapult arm. This way during our experimenting we wouldn’t have to change the arm. Picture of Model Data Collection Procedure 1. Gather all the materials to collect our data. 2. Put the catapult at the starting line/point, which is where we put to mark the starting point or 0 meters (0cm), then up to three meters after that. 3. Put the projectile or marshmallow on the catapults. 4. Pull down the catapult’s arm to a 45 degree angle, then release the arm. 5. Time the amount of time the projectile (marshmallow) takes to land. 6. Measure the distance the projectile traveled from the catapult to where it initially landed. 7. Record data. 8. Repeat steps 1-7 for as many cups there are (we had 4 cups). After collecting my data, I found that the average total velocity for the marshmallow was 11.8 cm/s. To calculate the initial velocity we set up the catapult with the arm facing the wall. We measured the length of each cup on the arm (the arm length different). Next, we timed how long it took the marshmallow to hit the wall. Then we used the formula D x T = V (Distance x Time = Velocity). In this case, the distance is the length of the arm and the time is how long it took the marshmallow to hit the wall. Charts: Independent Time 1 Variable/ Horizontal Time 2 Distance 1 Horizontal Average Average Distance 2 Time Horizontal Length of Distance the Arm(Cups) Cup 1 .47 sec. 108 cm .47 cm 85 cm 0.705 sec. 96.5 cm Cup 2 .37 sec. 80 cm .53 cm 95 cm 0.45 sec. 87.5 cm Cup 3 .41 sec. 80 cm .41 cm 78 cm 0.41 sec. 79 cm Cup 4 1.22 41 cm .41 cm 64 cm 0.815 sec. 73 cm Independent Time 1 Distance Initial Time 2 Distance Initial Average Variable/ Velocity Velocity Initial Length of 1 2 Velocity Arm (Cups) Cup 1 .35 sec. 45 cm 15.75cm/s .28 sec. 45 cm 12.6 cm/s 14.17cm/s Cup 2 .25 sec. 39 cm 9.75 cm/s .28 sec. 39 cm 10.92cm/s 10.33cm/s Cup 3 .25 sec. 33 cm 8.25 cm/s .34 sec. 33 cm 11.22cm/s 9.73cm/s Cup 4 .50 sec. 27 cm 13.5 cm/s .47 sec. 27 cm 12.69cm/s 13.1cm/s Data Analysis After collecting our data, we found that by changing the arm length we increased the range or distance that the marshmallow traveled. From our data, we can conclude that the longer the arm, the farther the marshmallow travelled. However, the longer that the arm was, the more time it took the arm to launch the projectile. During our experimentation we found that there are few limitations to our catapult, however our model was a challenge because you had to hold it down or weigh it down in order to launch the marshmallow without the catapult falling backwards and breaking. The base of the catapult couldn’t support the arm while launching the marshmallow. There were a few sources of error when we first did our experiment. These were that we forgot to launch the marshmallow at the best possible angle, so we weren’t getting the best results. Also we were not measuring where the marshmallow initially landed. This was a problem because it caused inaccuracy in our data. Conclusion Overall, my hypothesis was correct; that increasing the length of the catapult’s arm it did increase the range or distance. However, the longer the arm was the more time it took the catapult arm to rise to launch the marshmallow. I believe that the best solution to the Gorge problem, where there are stranded starving hikers across the gorge, is to make a catapult with a arm as long as possible and to launch the supplies over to them. Or to be more precise on the arm length, the arm should be about 164.5 meters. This is based off the fact that my catapult arm was .45 meters or 45cm and the marshmallow traveled over a meter (1.08 meters or 108cm). If you multiply my .45m catapult arm by the gap or the gorge, you should get 164.5 meters. A real life situation besides the gorge problem, would be during World War Two. Soldiers used catapults to launch grenades and gas bombs over long distances. The launch of these catapults would have to be precise because the soldiers needed them to hit their target or opponent. Through this project, I learned why catapults are important, as well as why and when they were used- which was mostly in wars or in the Gorge situation to save a life.