nctm 2012 presentation 3
DESCRIPTION
This is the third of the presentations we gave at the TI booth at NCTM 2012 in Philly.TRANSCRIPT
Algebra & Geometry Resources for the TI-Nspire
NCTM 2012WWW.MEDIA4MATH.COM
Algebra & Geometry Resources for the TN-Nspire
Media4Math includes a variety of free and premium resources, including short video tutorials on the Nspire, Math in the News, and other tutorials.
Algebra & Geometry Resources for the TN-Nspire
DVD Library, Algebra Applications.
Algebra & Geometry Resources for the TN-Nspire
DVD Library, Geometry Applications.
Algebra & Geometry Resources for the TN-Nspire
This presentation on the Titanic comes from the Geometry Applications: Area and Volume and includes algebra and geometry connections.
Algebra & Geometry Resources for the TN-Nspire
This illustration gives a sense of the size and scale of the Titanic.
Algebra & Geometry Resources for the TN-Nspire
To better understand how a ship of this size can float, we explore the concept of density.
Algebra & Geometry Resources for the TN-Nspire
By definition the density of water is 1 (in units of gm/cm3). A density less than 1 causes an object to float; greater than 1 and the object sinks.
Algebra & Geometry Resources for the TN-Nspire
As a simple example, look at a cube of length s and mass M. Its density is M/s3.
Algebra & Geometry Resources for the TN-Nspire
This is a rational function. Given different values of M, the cube will float based on where its graph is relative to y = 1, the red line.
Algebra & Geometry Resources for the TN-Nspire
We can estimate the volume of the Titanic by looking at the shape of the hull and main body of the ship.
Algebra & Geometry Resources for the TN-Nspire
A triangular prism provides a reasonable estimate of this folume.
Algebra & Geometry Resources for the TN-Nspire
This is the net for a triangular prism.
Algebra & Geometry Resources for the TN-Nspire
Given the dimensions shown, the volume of the triangular prism is found using this formula.
Algebra & Geometry Resources for the TN-Nspire
These are the dimensions for the Titanic. The linear dimensions are for the “rectancular prism” section and the displacement is the mass of the ship.
Algebra & Geometry Resources for the TN-Nspire
On the Nspire, create a Calculator Window and assign the values for mass to a variable called “mass.”
Algebra & Geometry Resources for the TN-Nspire
Make sure the units for mass are are gm. You can operate on the “mass” variable and reassign the result to the same variable.
Algebra & Geometry Resources for the TN-Nspire
Create a “volume” variable and calculate the volume of the triangular prism. Then calculate the density.
Algebra & Geometry Resources for the TN-Nspire
The estimated density of the Titanic is less than 1 (and probably a bit higher due to the triangular prism volume).
Algebra & Geometry Resources for the TN-Nspire
When the Titanic struck the iceberg a number of punctures caused water to flow into the hull.
Algebra & Geometry Resources for the TN-Nspire
When a ship takes on water, the loss in volume is immediately converted to mass. This leads to a quick increase in density.
Algebra & Geometry Resources for the TN-Nspire
This density expression shows that as the volume decreases, the mass increases. The variable x is the percent of volume lost.
Algebra & Geometry Resources for the TN-Nspire
This graph shows that when about 58% of the hull is filled with water, it will sink. But this overestimates the volume of the hull.
Algebra & Geometry Resources for the TN-Nspire
This graph scales the volume down and gets us to a more accurate estimate of when the ship will sink.
Algebra & Geometry Resources for the TN-Nspire
The Titanic had 16 watertight compartments. When it struck the iceberg, 5 (possibly 6) of them were punctured.
Algebra & Geometry Resources for the TI-Nspire
NCTM 2012WWW.MEDIA4MATH.COM