Experimental Process: Read following instructions for the experimental portion of this activity. Document all of your trials in your Engineering Notebook (or Journal) with illustrations and/or a table to log various positions of fulcrum. Be organized in your approach so that you can easily discover patterns as they are occurring (do not just move fulcrum arbitrarily ...having a strategy of chronological incremental movements is best).
Record all of your thoughts and difficulties as you go along for later reflection in the Understanding Leverage Blog link located at the end of this activity.
To the left is an example of a first class lever.
Although there are other arrangements for levers...other classes...We will focus on the first class lever for the purposes of this experiment.
Using you ruler as the lever itself, the pencil as the fulcrum, and the washers as your weights (you should have 10 identical washers) experiment with the relationship between location of fulcrum and the ratio of washers on each side of the lever when a tipping point is discovered. Washers must always be stacked onto the very end of the ruler to avoid data confusion.
It is best to use a structured approach to recognize patterns as they emerge If we start with all washers on one side of the lever and begin gently lifting them one at a time and then gently placing them on the other side, at some moment (either when lifting a washer...or placing a washer) your balance will shift causing the lever to tip from one side to the other.
When this tipping point is discovered, at that moment record the number of washers on each side of the fulcrum.
Each scenario (station) should have a dedicated table row, or illustration, to log your data into. This illustration is an essential part of the evaluation. It must be understandable by a reader without your presence or verbal explanation required. Your documentation must stand alone and be sufficient for your experiment to be repeatable by others.
After recording your data move the fulcrum to the next position, (It is suggested you move your fulcrum at 1 inch even increments for ease of analysis and later calculations) repeat the washer activity and record your findings. You should have a total of 10 stations recorded before your data is complete. At this point you and your partner(s) should examine the data collectively to discuss patterns you may realize.
Experimental Synopsis: Students will form various arrangements of a first class lever with their given materials (fulcrum between E and R) then the load all washers to one side as the "R" being at various distances from the fulcrum, with each variation distance being recorded by using graduations on the ruler. The the washers shall be transferred one at a time to the "E" side until equilibrium is disrupted (tipping point attained).
Note: It is suggested that which ever side is chosen (left or right) to be the "R" should remain the same throughout the experiment to avoid confusion in analysis and pattern recognition.
For each arrangement the following shall be recorded for analysis:
The length from the fulcrum to the load LR
The length from the fulcrum to the effort LE
The number of washers used as the load R
The number of washers used as the effort E
Formulating Conclusions: After the class presentation then look at the worksheet below...use the experimental information combined with our recent class discussion to attempt to complete the linked worksheet activity below.
Once you have completed the above experiments, discussions, documentations and worksheets...then reflect upon what you have learned and what difficulties you overcame on the class page discussion post link below:
If you are secure with these problems or want to extend your knowledge or challenge yourself, then click the links below and explore the sites for a while. After a while you can try some of these problems / questions below:
oList an additional three examples of each class of lever.
o List an example(s) of some compound machine made of:
- 2 simple machines
- 3 simple machines
- 4 simple machines
o For each of the above examples list the simple machines which combine to make the aforementioned compound machines.
o For each of the above examples describe where these simple machines exist within the compound machine, and how the simple machine is used as a part of the process which the compound machine is being used to accomplish.
Artifact Presentation and Reflection:
A gallery walk of each groups Experimental Data Artifacts followed by a group discussion about the various approaches and uniformity. After reflection and group analysis, construct a final presentation documenting your process and what new things you have learned about Geometry and Excel Spreadsheets for your class and teacher. Your presentation artifact shall be a PowerPoint presentation of no less that 5 slides and no more than 15. Your presentation should address all factors considered and how looking at the other groups work may have affected your final analysis.
All PowerPoint presentations should be of professional and conservative business or scientific format. These shall then be posted on an ongoing web based class project site and each persons personal web portfolio for display on the internet. All pages and portfolios shall conform to internet safety standards and acceptable language and content policies.
A formal peer review shall be done as a discussion post on the class webpage and shall be completed appropriate to said venue with regard to commentary, language and content. This review/reflection is to be a graded activity of self and peer assessment skills.