S0.1.1 - Lab Skills

Centimeters to Inches

Choose an object from within the room that you will be able to measure the lenght of at least one side.
In your data table, describe the object so that another student would be able to find the object.
Measure one dimension of the object in the units of inches (convert the fraction of an inch into a decimal). Record this value in your data table.
Repeat the measurement of the same dimension in the units of centimeters (record to 0.1 cm). Record this value in your data table.
Repeat this process for a minimum of 10 lengths / dimensions.
Using Desmos, graph your data as described to the right.
Describe the significance of the slope of the best fit line of the graph.

Here's how to create a scatter plot in Desmos, with a focus on simplicity and clarity:

Open the Desmos Graphing Calculator: Go to desmos.com or open the Desmos app.
Add a Table:
- Click on the "+" sign (Add Item) in the top left corner.
- Select "Table" from the options.
Input Your Data:
- Enter your x-values in the first column and your corresponding y-values in the second column.
- Tip: If you have data in a spreadsheet (like Excel or Google Sheets), you can copy the columns and paste them directly into the Desmos table, according to the Desmos Help Center.
Visualize and Adjust:
- Automatic Zoom: Clicking the magnifying glass in the lower right hand corner of the Table section will automatically fit your data to the screen.
Add a Best Fit Line:
- Using the

Choose one of the unknown solutions.
Add a small amount of the solution to a graduated cylinder. Record the volume of the solution in the graduated cylinder
Using an electronic balance, measure the total mass of the cylinder and solution. Record the mass.
Add an additional small amount of solution to the graduated cylinder. Record the new volume.
Using the electronic balance, measure the total mass of the cylinder and solution. Record the mass.
Repeat for a total of 6 different volumes.
Graph the data using Desmos.
Describe the significance of the best fit line and the y-intercept of the data.

Given that these solids are irregularly shaped, how will you accurately determine their volume? Think about methods you've learned for measuring the volume of an object that doesn't have a simple geometric shape. What tools will be essential for this?
Once you've determined a method for finding the volume of each rock, how will you ensure your measurements are precise and consistent for each solid? What challenges might you encounter when measuring the volume of an irregular object, and how can you minimize errors?
Besides volume, what other fundamental property of each rock will you need to measure to determine its density? What instrument will you use, and what precautions should you take to get an accurate reading?

As you measure each rock's mass and volume, how should you organize your data to prepare it for analysis? What columns would be useful in a data table?
Thinking back to the liquid density lab, what two variables will you plot on your graph (one on the x-axis, one on the y-axis) to establish a linear relationship that will help you find the density of the rocks? Justify your choice for each axis.
What do you expect the shape of your graph to be? Why? What physical principle suggests this specific graphical relationship?
What do you anticipate the y-intercept of your graph will represent in this experiment, assuming you are plotting the mass of only the rock against its volume? Why might it be different from the y-intercept in the liquid density lab?

Once you've created your best-fit line, what physical quantity does the slope of your graph directly represent? Explain how the units of the slope correspond to this physical quantity.
How will you use the equation of your best-fit line (y=mx+b) to explicitly determine the density of the unknown rocks?
What does the R2 value tell you about your experiment? How does a high or low R2 value impact your confidence in the determined density?

How will you obtain the known values for the densities of common rocks or minerals? What resources might you consult (e.g., textbooks, reliable online databases)?
Once you have your experimentally determined density and a set of known densities, how will you compare your results? What are some ways to quantify the accuracy of your measurement?
Based on your experimental density and comparison to known values, can you identify the most likely type of rock you investigated? What are the limitations of this method for precise rock identification?
Beyond measurement errors, what other potential sources of error or uncertainty might have influenced your determined density? (Hint: Think about the assumptions made in the water displacement method.)

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