Coulomb's Law

Today we talked about Coulomb's Law and polarization.

Notes: Coulomb's Law

Coulomb's Law is the most math-intensive part of this unit, so we will also be practicing Coulomb's Law problems tomorrow. Remember that tomorrow is the last day of the quarter, so if you have anything you want to get onto the quarter grade, turn it in now. I will do my best to grade everything that is turned in before I go home on Thursday, but I might not make it. The earlier you turn in your work, the sooner I'll get to it.

Homework tonight is Chapter 15 (p. 541) #1 & 4

Electrostatics Intro

Today we introduced the electrostatic unit by making balloons attract and repel, then talking about why what we did worked. The explanation involves net charge, transfer of electrons, and the fact that like charges repel and unlike charges attract.

Then people started on their homework while I passed out missing assignment reports and took care of assignments people found.

Homework is in two parts:

Chapter 15 Conceptual #1 & 2 - you will turn this in tomorrow
Read Sections 15.1 & 15.2 and take notes. These will NOT be collected.

Chapter 14 Practice Exam

Monday is your test for this chapter, so below you will find our usual practice exam and solutions videos. This test is shorter than normal, consisting of 9 multiple choice problems and two free response; think of it more like a quiz than a test.

Ch. 14 Practice Exam

Answer Key:
1. 817 Hz
2. 38 m/s

Solutions Videos:
#1
#2

Remember that your Speed of Sound in Air lab is due Monday.

Lab: Speed of Sound in Air

Today you are working on your lab! You can find a copy of the lab here.

On the board there were some hints to help you finish in time, but you can also work on this tomorrow when I give out the practice exam.

There is no additional homework. The lab is due Monday.

Resonance and Beats

Today we are going over the last two topics in this unit: resonance and beats. We've already touched on both of these, but here are some notes:

Notes: Resonance and Beats

Tomorrow we are doing a lab, so tonight's homework is to do the pre-lab.

Lab: Finding the Speed of Sound in Air

On Friday I will pass out a practice test and you may also continue to work on your lab, which will be due Monday. Your test for this unit is currently scheduled for Monday.

Standing Waves

Today we talked all about standing waves:

Notes - download and run as a slideshow

We will be using the information about the standing waves produced in a tube closed on one end for a lab next class.

Homework is Ch. 14 (p. 509) #38, 41, 49, 53

Interference of Sound Waves

On this last day before a four-day weekend we talked about why and how sound waves interfere when their path lengths differ to a given spot. This is why the walls in auditoriums, music halls, or anything else where the sound quality matters are not smooth. If they were smooth, different sound waves from the same source might reflect off the walls and make it to the same point (listener) by paths of differing lengths, where they would interfere and make the volume weird.

PICTURE HERE - SOON

You don't have any real homework this weekend, but it would be nice (if you have a smartphone) if you could find and download an app that lets you produce sounds of known frequency - a frequency generator. There should be some free ones out there. This is for a lab I want to do next week (although probably not the day we get back).

I am also looking for buckets and PVC pipe (2-4 ft long) for that same lab. You would get those supplies back.