## November 24, 2008

### Misprint on homework

I have a misprint on the homework due Wednesday- in the first problem, I define apparent weight to be the true weight of the object plus the buoyancy force- it should be MINUS the buoyancy force. Weight is a force fdirected downward. You should find that the concrete blocks have a positive apparent weight (just like any of us have a positive apparent weight standing around in air) and the steel sphere float will have a negative apparent weight.

jay-

## November 20, 2008

### Practice exam

The practice exam (with some annotations) is posted on the website. Also, a cheat-sheet for tomorrow's exam.

jay-

### Homeworks, keys, etc

Homework 12 is posted, as is a key to homework 11.

I've recently seen three videos which all look like great exam questions. Take a look at these, and think about the physics (or lack thereof) behind these:

http://failblog.org/2008/11/19/shopping-cart-fail/

http://failblog.org/2008/11/18/logistics-fail/

http://failblog.org/2008/11/17/cable-fail/

jay-

## November 13, 2008

### homework stuff posted

Hello everyone-

Homework 11, and the key to homework 10, are now posted on the website.

In answer to several people's questions: yes, there's an exam next friday. It will cover rotation and statics.
We'll discuss it tomorrow and hopefully we'll be able to fit in a practice exam.

jay-

## November 11, 2008

### Problem for Wednesday

Hello everyone-

I'll start lecture on Wednesday by discussing problem 7, which is very similar to the ruler problem we did in class on Monday.

jay-

## November 7, 2008

### Homework 10 posted, cross products

Hello everyone--

I just got homework 10 posted.

A few people have asked that I go over cross-products, so we'll do a short review of the idea of a cross-product on Monday.

We will be starting on Statics on Monday- we're only a day behind the reading schedule right now. Make sure you've read 10.1-4.

We'll also go over problem 11.60 on Monday, and I'd like to add the following question to it: How much energy is there in the system before and after the student walks to the center? Is the amount of energy in the system the same or different, and why?

jay-

## November 6, 2008

### Homework 9 key; problem for tomorrow

Hello everyone-

The key for HW 9 is posted; I'll post HW 10 problems first thing tomorrow.

Tomorrow, I am going to start the lecture by discussing the following problem:

You fire a bullet, of mass 9.00g, at 860m/s into a wooden door of mass 18kg and width 0.85m. The bullet hits the door at a right angle, 0.75cm away from the hinges (the axis of rotation), and becomes lodged in the wood. The hinges are frictionless, of course. What is the resulting angular velocity of the door?

## November 4, 2008

### Homework delayed (again)

Hello everyone-

I didn't get through as much stuff yesterday as I would have liked. I'd like to postpone homework 9 until Thursday so that we have a chance to talk about a few more concepts tomorrow before you have to turn it in.

jay-