Week+2+Spring+2010

=Week 2 Spring 2010=

We've started the new session studying momentum. Momentum can be defined as inertia in motion. Something must be moving to have momentum. Momentum is how hard it is to get something to stop or to change directions. A moving train has a whole lot of momentum. A moving ping pong ball does not. You can easily stop a ping pong ball, even at high speeds, it is difficult, however, to stop a train even at low speeds. Mathematically, momentum is mass times velocity, or Momentum=mv. The heavier something is and/or the faster it’s moving the more momentum it has. The more momentum something has the more force it takes to get it to change velocity and the more force it can apply if it hits something. Last week we played with momentum by crashing balls into other balls and seeing what happens when momentum is transferred. This allowed us to also take a look at the concept of conservation of momentum. This week we played with momentum again by creating vehicles. I challenged the group to create a vehicle with the greatest amount of momentum and then we rolled it down a ramp to see how far it went. The vehicle with the most momentum went the farthest.
 * Recap from Jim:**

Here is the recap of the Modeling part of the second meeting. The big idea we explored was the physics/math system for dealing with space and movement in programming. Here I summarize what group members said.
 * Recap from Maria:**

We describe POSITION by coordinates, and there are typically two or three of them. Such variables with many parts are called "vector variables."

Difference between two POSITIONS is DISTANCE. It is one number (not two or three), so it's a scalar variable.

Moving given DISTANCE over a particular TIME makes VELOCITY. Changes in POSITIONS over a particular TIME also make VELOCITY. (I am not being eloquent enough here - maybe Jim can help next time). Thus two ways to program VELOCITY: either by changes in each of the coordinates, or by moving "that many steps" (a distance) in a given direction.

Changes in VELOCITY over a particular TIME make ACCELERATION. Again, there are two ways to program it, either through coordinates, or through steps and direction.

Changes in ACCELERATION over a particular TIME make JERK. Hence, the awesome physics insult: "You are such a change in acceleration!"

You can keep going forever, but you probably won't need models that detailed until you program a real Mars lander or some such. People who do go to the fifth or so step, called "derivative."

~*~*~*~*~* HOMEWORK has to do with exploring these notions and preparing to model the forces

1 - Please upload your pictures from the meeting to this week 's page on our wiki here. Write a couple of sentences about your picture (a caption so people know what it's about), something like "Momentum and I." 2 - Scratch track: use our old "Dripping faucets" applet http://scratch.mit.edu/ projects/NaturalMath/715530 and make water drops MOVE SMOOTHER or LESS SMOOTH. What does "moving smoother" mean in terms of position, distance, time, velocity? Post your applets to our Scratch group. If you have questions, find Scratch TAs: Trevor and Katherine. 3 - Python track: finish at least four chapters of the book at http://inventwithpython.com doing all exercises you deem interesting. If you have any questions, the book author, Albert Sweigart, said he will answer your questions by email. Let him know you are in Natural Math modeling group, please. Contact Python TAs with questions: Daniel and Hannah Look at the first video tutorial Benjamin sent, found at http://showmedo.com/ videotutorials/video?name= pythonThompsonVPython1& fromSeriesID=30 Get the source code linked there and implement it. Make the object move in either SMOOTH or "STOP-MOTION" fashion by changing the script. Post your programs here: http://physicsmathmodeling. wikispaces.com/Our+Python+ program+gallery

~*~*~*~*~* Trevor and Hannah are planning the ice field trip. Stay tuned.

~*~*~*~*~* Nina is bringing snacks next week. Yay snacks! Thank you for setting up the sign-up calendar, Nina.