Bill Goodwine's Courses

Posted: **Fri Sep 23, 2011 4:29 pm**

Reading: You should have read everything from Chapter 1 through Chapter 4 by now. The first exam will cover this material.

Exercises: 4.3, 4.4, 4.7, 4.9, 4.10, 4.12, 4.14, 4.19 and 4.22.

Posted: **Tue Sep 27, 2011 4:18 pm**

Can you give a suggestion on how to solve Problem 4.14? I do not know where to start.

Posted: **Tue Sep 27, 2011 5:12 pm**

Also, I'm confused as to how to solve for the homogeneous solutions in Problem 4.22 because it involves x and y terms. How should we do this?

Posted: **Tue Sep 27, 2011 5:40 pm**

pat wrote:Can you give a suggestion on how to solve Problem 4.14? I do not know where to start.

Write F=ma for the board. The forces on the board are at two points due to friction by each roller. If the board moves the normal force supported by each of the rollers changes.

I actually had this on the final exam one year.

Posted: **Tue Sep 27, 2011 5:40 pm**

pat wrote:Also, I'm confused as to how to solve for the homogeneous solutions in Problem 4.22 because it involves x and y terms. How should we do this?

I emailed the whole class about this one.

Posted: **Wed Sep 28, 2011 5:38 pm**

On 4.12 are we supposed to account for the gravitational force?

Posted: **Wed Sep 28, 2011 7:57 pm**

What are you looking for when you say to get approximations to steady-state solutions for equations by looking at graphs like in 4.4 or 4.7? There's nothing remotely similar to that problem in the book or what we did in class. thanks.

Posted: **Wed Sep 28, 2011 8:25 pm**

astumpf wrote:What are you looking for when you say to get approximations to steady-state solutions for equations by looking at graphs like in 4.4 or 4.7? There's nothing remotely similar to that problem in the book or what we did in class. thanks.

The graphs present all the information you need for the steady-state solution. The "approximation" partly only means that you can only approximately read the values from the graphs. Just ask yourself what those graphs are showing.

Posted: **Wed Sep 28, 2011 8:29 pm**

Someone asked me:

For homework question 4.9, it asks to find the equation for motion for figure 4.25. When doing this, do we take into account the forcing function and the gravity separately or do we assume that the forcing function in the figure is the force of gravity? Thanks!

Gravity and the forcing function are supposed to be separate.

Bill Goodwine's Courses

Homework 5, due September 29, 2011.

Homework 5, due September 29, 2011.

Re: Homework 5, due September 29, 2011.

Re: Homework 5, due September 29, 2011.

Re: Homework 5, due September 29, 2011.

Re: Homework 5, due September 29, 2011.

Re: Homework 5, due September 29, 2011.

Re: Homework 5, due September 29, 2011.

Re: Homework 5, due September 29, 2011.

Re: Homework 5, due September 29, 2011.