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to the Top.A Web Quest for Physics Students
Created by Steven M. Millam
for EMC 598 at ASU West
Instructor: Dr. Alice Christie
completed on 9 July 1999
Introduction | Task | Process & Resources | Evaluation | Conclusion
Introduction: The world pays a lot of attention ( and money) to a "good shot," whether it be Michael Jordan, a medieval ballista, or the Army's latest artillery piece. Michael Jordan develops his skills as a "good shot" by continually practicing. The ballista was developed through trial and error. However, in modern days, advancements are made through research and development even before a prototype is developed. The scientists and engineers who develop artillery pieces for the Army begin with expert-level knowledge of physics, namely forces, projectile motion, strengths of materials, etc.
As physics students, you will build a thrower from scratch, study it so that you can predict where the projectile will land for a given setting, and then "sell" it to your classmates. There are many steps involved, but you will enjoy the experience and learn much in the process.
The Task: These are the steps that you need to complete. Be sure to do them in the given order. From time to time, you will need to take on different positions. You will receive a grade (see Evaluation below) for participation, appropriate behavior in the library, and equal division of the work.
Group size: 3-5 students (4 is probably ideal).
Before you jump in: Many of these steps can be divided into various jobs. I would recommend that you do that while still working together as a group. You may want to read through the entire procedure and assign various tasks in advance (they can be changed later, if necessary). It is important that you divide the tasks evenly and take into account the various talents of your members. For example, let your best artist draw the pictures (steps 1 and 4), the best English student write most of the text (step 2), and the best engineer construct the thrower (step 5). This is not to say that you work alone! I am merely suggesting that you take advantage of the talents available to you!Step 1. Your first step is to discover what other cultures have done throughout the years. Why reinvent the wheel? You might be surprised by the number of different variations of each type of device that has been developed and the cultures that developed them! Write a one page summary of each time period with at least one diagram from each period (your choice of the type of thrower).
Jobs: You may want to assign each time period to one person.
The Greeks
Catapults: Tension Artillery and the KatapultosThe Romans
Rome and BallistasMediaeval Times
-The Goodrich Castle in England: Read the text to discover some of the history of castles and see some of their structures.-A site for lots of information about castles in Wales.
-Archive of Ancient Technology. Contains a large number of pictures of genuine mediaeval objects. Scroll past the initial text to a list of images. Look for "ballista" and other pertinent words. Explore a little!
Ballista Pictures: first and second (a different type)
Pictures of various trebuchets: first, second (in siege), and third
Animation of a trebuchet in action.
Modern Structures
Ballista 1Discussion of the Modern Use of Catapults
A variety of modern trebuchets
A large pictureA picture of the motion of a trebuchet
Websites containing a wealth of information about how to build a trebuchet:
A MUST READ! The Grey Company Trebuchet Page. This site contains historical photos and text relating to them. Be sure to carefully examine each hyperlinked site in the index.De Trebuchet by Codesmith.com A series of pictures, no text.
Trebuchet.com Be sure to click on "More Information and Pictures."
The Millenium Project's construction of a trebuchet. Use the arrows at the bottom to maneuver around the site.
Step 2. Now you will need to research the following topics from your textbook and write a paragraph about each. A paragraph consists of at least 4 sentences. In the Conceptual Physics textbook by Paul Hewitt, these would be found in chapters 2, 3, and 8.
TOPICS: forces (in general), force of gravity, inertia, acceleration, projectile, projectile motion, and vectors.In addition, examine the following site and write a one page summary of the contents. The Physics of the Trebuchet. Be sure to examine "Principles of Motion" and the various figures with discussions.
Step 3. By now you may have some ideas of what your thrower is going to look like. But before you build it, you should submit your ideas to an expert and seek his or her insights. Also, if you have any questions that the textbook or website was not able to answer, then you may ask the expert. Everyone should work together on this and listen to each person's thoughts and questions.
Ask an Expert. The last time I checked, there were 71 different science sites listed. Therefore, it is important that you browse the entire list and write the the person who is most qualified to answer your particular question! For example, writing to the "Ask a paint expert" probably would not help you here!!Ask Mr. Science. This is a great site for students to ask science questions of an expert.
Step 4. Once you have received a reply from your expert, and shown it to me, then you are ready to "construct" your thrower on paper first. However, here are the parameters that your device needs to meet:
- We are not building war machines!
- The primary goal of your thrower is hitting a target, not distance, height, or damage to the target! However, you will not know the exact distance of the target until the day that we test your devices. Your object will need to hit inside of a medium hula hoop that is located between 2 and 7 meters from the launch site.
- The object to be launched on test day will be a 0.5 kg mass.
- Now draw a detailed diagram of your thrower and label each part. You should consider what materials that you have available to you for the platform, the "arm," the "force" behind the throw, etc.
- You need to describe how you will be able to adjust the range that your thrower tosses the object.
- When your diagram is made, submit it to the teacher before moving on to Step 5.
Step 5. Now you are ready to actually build your thrower! You will need to thoroughly test your thrower so that you are confident that it can hit any target within the range. For example, can it hit the target if it is placed 2.5 meters from the launch site, and then be readjusted to hit another target that is 6.5 meters away? Your goal is to be able to hit either target. Your steps are:
- Build the thrower.
- Keep a journal from this point on. Record your insights, innovations, frustrations, successes, and the data (see below). Your journal does not need to be too detailed--just the highlights and data!
- Test it at "force levels" to see what range they correspond to. This is called calibration! You are to keep a data table of all your trials. This is required!! Your "force levels" might be in terms of angles or meters. For example:
Angle from Vertical (degrees)
Launch Range (meters)
30.0 deg
2.4 m
40.0 deg
3.1 m
50.0 deg
4.2 m
- Record your data on a spreadsheet in a similar format above.
- Monitor and record sources of error, such as friction, wind effects, uncertainty in measurements, etc. Describe how you would improve them next time (if you can not do it this time!). Record in your journal.
- Graph all of your data using the spreadsheet functions.
Step 6. On a specified day, after most of the lab groups have completed steps 1-5, your teacher will announce a day for testing your thrower. Again, your goal is to adjust your device so that it can propel the 0.5 kg object into the hula hoop located at a specific distance from the launch site. You will be graded on the thrower's accuracy. Remember: this is not your only grade! See the "Evaluation" section below. Record the location of the landing. The teacher will provide a camera if you would like to use it.
- If your thrower did not perform well during the test, then you will have more time to fix it up and retest it.
Step 7. Now you are going to "sell" your thrower to your classmates (or maybe to another physics class). Your sales presentation should include the following:
- A "fancy" diagram of the final model of your thrower.
- A digital photo of your thrower, either scanned from a normal print or taken with a digital camera.
- A concise description of the physics principles that are involved with your device.
- Your spreadsheet data table and graph.
- Your "official" results from Step 6. That is an official account of your thrower's performance (just like the rating from the Consumer Product Safety Commission).
- The rest is up to you! You can include music, PowerPoint* "slides," posters, costumes, etc. Of course, normal school decency rules still apply.
- "Sell" your product to the class! Your classmates will make silent "bids" on your device and you will later be told what the highest bid was (not the bidder). The amount of the bid does not affect your grade. Your teacher will grade only the quality and the content of your "sales" presentation.
Evaluation. Click here to go to the evaluation rubric that will be the basis of your final grade.
Conclusion. Your final assignment, as individuals, will be to write a short summary of your lab experience. The conclusion should include what you learned about other cultures, the various launching devices, and what new concepts you discovered during the process of designing your thrower. Finally, describe some ways that you would improve the performance of your thrower (including accuracy, range, and safety). All together, your conclusion should be at least 2 pages long, double-spaced, and normal size 12 font.
Purpose: This Web Quest is designed for advanced students taking Physics in High School.My goals were to:
1. Have students demonstrate an understanding of the development of various types of throwing devices.
2. Have students learn specific topics related to the physics of a throwing device.
3. Have students practice data collection, error analysis, and organization of data on a spreadsheet.
4. Challenge the students to accomplish a specific physics-related task as part of a collaborating team.
5. Provide students with different "bents" an opportunity to help their group according to their special talents.
6. Have students connect some of the abstract physics concepts with the real world.
7. Motivate students to study physics beyond this class.
