INVESTIGATIVE QUESTION: How precisely can we determine the coefficient of static friction and the coefficient of kinetic friction using classroom materials?

Finding the coefficient of static friction:

• A wood block is placed on some sort of surface placed on your desktop.

• The surface is slowly tilted until the exact moment (as best as can be determined) that the wood block starts to slide down that improvised ramp

• Work with you team the basics for this part of the investigation - how does the measurement of static friction work generally? (Think about yesterday's test-- also that engineering site I had you take a gander at last week can be MOST helpful).

• We'll take a while for you to work through this part during out pre lab today. Much sketching, much discussion before we move on to the next step. It's REALLY important that everyone on your team thoroughly understands the basics of static friction before we proceed.

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• You must provide a mathematical basis/derivation of WHY we are choosing to use this method. We did this together in class however the entire derivation MUST be included in your methods section (Note: This is not a calculation so please do not include this in your sample calcs section)

Finding the coefficient of kinetic friction:

• A plywood block is placed on some sort of material placed on your desktop.

• That block is connected by a piece of string to a mass (or masses). The string goes over a pulley and the mass(es) hang down vertically and the plywood block is allowed to move freely.

• You must provide a mathematical basis/derivation of WHY we are choosing to use this method. We did this together in class however the entire derivation MUST be included in your methods section. Keep in mind this is most definitely NOT the same calculation that we used as a basis for finding the coefficient of static friction. (Note: This is not a calculation so please do not include this in your sample calcs section)

General notes for the lab.

This is 1.5 x lab. That means it isn't quite a double lab but it is almost a lab-and-a-half and will be scored at 1.5 x a normal lab. Since a regular lab (with a graph) is worth 30 points, that makes this lab worth 45 points.

That makes this lab, by far, the highest point value assignment we will do all semester (and probably all year!)

The breakdown is as follows:

This lab will (obviously I hope) have a substantial impact on your grade.

Notes on the the report format:

1. Please use the format shown on the sample report HERE. Learning to write to a specific standard is an important skill to develop. If my example shows something as bold and using Roman numerals then your report must also show that same item as bold and using Roman numerals (for example)

Notes on the graph:

Graphing these results can be a wee bit tricky. We'll talk about basic graphing strategies and such AFTER we've collected our data.

1. Please do NOT collaborate with anyone on making your graph (see below). I'm grading you on how well you've developed your physics graphing skills this year.

2. Your graph should clearly and succinctly summarize your results in a way that an interested observer/reader (like, well, ME for example) will be able to understand your results very, very easily.

3. Please note, if you find there is no correlation (that is known as a NULL result in science) then your graph should reflect that. Be careful, if your data shows no correlation when there is one, that will work against you. Likewise if your data shows a correlation when there isn't one, that will likewise work against you.

Notes on collaboration:

1. Please *do* collaborate on all parts of the lab with the exception of the graph and the discussion sections.
2. You MUST work on those by yourself without assistance from your team on those sections.
3. If a team mate (or anyone else for that matter) asks that you send them your lab report for any reason ("Please send me your report, I'll only grab the data") you MUST decline. That is plagiarism.