### How do we find the density of an object? What other kinds of densities exist?

posted Oct 19, 2017, 6:58 AM by Barbara Fortunato
2: T 10/24

Today, we'll review what you know about density and introduce the concepts of linear and surface densities.  We'll perform a lab that requires you to measure, estimate, and find other information.

Then, we'll break into groups to solve center of mass problems from Chapter 9:

Required: 59, 61, 62, 64, 65
Enrichment: 66, 67

These problems will require you to use the calculus and what you learned about different kinds of densities.  You may want to look at the following videos for reference:
If you have not yet done so,  watch the following videos on finding the center of mass of an object.  The first video shows you the theory on finding the center of mass.  The second video shows you how to find the center of mass of an object using the summation.  The third and fourth videos show you how to use the integral to find the center of mass.  Sorry for the long homework.  We need this information for next week.

#### Center of mass with integral, part 2 (vkiledj)

Homework:  QUIZ on Static Equilibrium on Friday, October 27th.  Watch the video below on rotational kinematic variables.  Take notes while you watch!  Understanding these concepts are EXTREMELY IMPORTANT in being successful in the rest of this unit, so take the time to rewind and rewatch as needed.  (When Mr. Fullerton derives centripetal acceleration in minute 13, he talks about unit vectors.  "I-hat" is a unit vector magnitude 1 in the x direction.  "J-hat" is a unit vector magnitude 1 in the y direction.  Unit vectors are really just multipliers which turn scalar magnitudes into vectors with direction.)