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### How can you find the mass of a mystery object using tension at an angle?

posted Dec 1, 2017, 10:29 AM by Barbara Fortunato
5: Th 12/7, 7: Th 12/7

Today, we'll look at how Newton's Second Law acts in two dimensions by performing a lab where we try to find the mass of a mystery object using two dimensional forces.  See below for set-up

If you have any trouble understanding the calculations here, check out the following video below.  The strategy is to draw a free body diagram of the knot.  (If the knot is made out of ideal or massless string, it does not have a force of gravity on it.)

#### Static equilibrium Y-Tension ‎(Michael van Biezen)‎

Homework:  Finish your lab write-up in your lab notebook.  Answer the following questions as part of your analysis:  (1) As you pulled the strings so that the angle between the strings increased, how did the tensions change?  (2) Is it possible to pull the strings so that both strings are horizontal?  Why or why not?  Then watch at least the first 19 minutes of the video below the homework section.  Take notes while you watch, and utilize the pause and rewind buttons as needed.  In this video, we’ll look at how we can apply what we know about vectors in two dimensions to inclined plane problems. The key to inclined plane problems is picking a coordinate system that makes sense.  We must shift our thinking from a traditional horizontal-vertical coordinate system to a slanted coordinate system.