Professor Kate Poirier | OL67 | Fall 2020

# Category: Announcements (Page 3 of 11)

Jian Hui asked a question from the Practice Springs WeBWorK set last week. At first I thought there was a mistake in the question, but it turns out I was making a mistake with units in my setup.

Here’s my description of the setup, which answers the first part of the problem.

You still have an initial value problem to solve for the second part of the problem, but now this is almost just like the initial value problems you solved in Chapter 5 when you were solving second-order equations.

One difference is that you need to convert your particular solution to a single cosine function like equation 6.1.10 in the textbook. Follow from the bottom of page 270 to the middle of page 271 to see how to do this.

You may have noticed that when you log into WeBWorK now, you see that all old WeBWorK homework sets have been reopened. While it looks like the sets are now due on two different dates, please notice that they’re due only one minute apart. (This is just so that the newest sets still appear at the top of the page.)

• All the Laplace Transform sets are now due Sunday, December 13 at 11:159pm.
• 11-LaplaceTransforms
• 12-InverseLaplaceTransforms
• 13-PartialFractionDecomposition
• 14-LaplaceIVP
• All the old sets are now due one minute later on Monday, December 14 at 12:00am.
• 1-FirstOrderLinear
• 2-SeparableEquations
• 3-TransformNonlinearToSeparable
• 4-ExactEquations
• 5-BasicSecondOrder
• 6-SecondOrderRepeated
• 7-SecondOrderComplex
• 8-SecondOrderNonhomogeneous
• 9-SecondOrderVariationOfParameters
• 10-SeriesSolutionsRegularPoint

## Test #3

Thursday, December 3 & Friday, December 4

Test #3 will cover material from Sections 6.1, 6.3, 7.2, and 7.3.

There will be three questions: one spring question and one circuit question from chapter 6 and one series solution one from chapter 7. You will answer only two of the three questions.

Other than the number of questions, the structure of Test #3 will be exactly the same as that for Tests #1 and #2. The Test #3 checklist with interview sign-up sheet and upload link will be posted next week.

## Test #3 review assignment

Due on the OpenLab Sunday, November 29

Your Test #3 review assignment is almost the same as the review assignments for Test #1 and #2 (the instructions for the Test #1 review assignment are here).

You will share your complete solution to one problem on the OpenLab. Choose one problem from:

• the WeBWorK set Practice Springs
• the WeBWork set Practice Circuits
• textbook homework from Section 7.2
• p.329: 1, 3, 8, 11-13, 19-25 odd
• textbook homework from Section 7.3
• p.338: 1-5 odd, 19-23 odd, 33-37 odd, 41-45 odd

(Note that the WeBWorK sets Practice Springs and Practice Circuits are optional and will not count toward your WeBWork grade)

Don’t forget to add the category Test #3 Review before you publish your post

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