I am going to try posting the lab as a blog post like this. If it doesn’t work, I will do something else.

Really, there are two objectives in this lab.

## Collecting Data

The first thing is to practice and become familiar with the tools you will use to collect data. We will use the Vernier motion detectors quite a bit. I will show you how to use these.

Things to do:

- Put a cart on a track and move it away from the detector. Which way is a positive x-velocity?
- Move the cart back and forth. Make a plot of position vs. time. See if you can predict what the velocity vs. time and the acceleration vs. time graph would look like. Use Logger Pro to check yourself.
- What would you have to do to the cart to make x vs. t graph a straight horizontal line?
- What would you have to do to make the v vs. t graph a straight horizontal line?

Another motion:

- Now give the cart a little push and let it roll on the track. Try to make the track level.
- Determine the x-velocity of the cart after you pushed it.

Fan carts:

- Turn on the fan and release the cart from rest. Record a graph of x vs. t and v vs. t.
- In a one-second interval, what is the change in momentum? Could you write this as a vector?
- In a two second interval, what is the change in momentum? Does it matter which 2 second interval you choose?
- Can you find the net force during these intervals?

Turn the fan around.

- Now give the cart a push.
- Record x vs. t and v vs. t graphs.
- Compute Δp during several time intervals (including some while the cart comes back towards the detector.
- For all the Δp that you calculated, how does the net force compare?

## Numerical Models

Maybe you should start by watching this very excellent video.

computation introduction 4 from occam98 on Vimeo.

And here is another post about numerical calculations: http://www.wired.com/wiredscience/2008/10/basics-numerical-calculations/

What to do next? I put a pdf file in blackboard with the rest of the instructions.