• PTSOS Photos - January 22, 2011

• PTSOS Photos - January 31, 2009

• Photos of the Rocket That Didn't Launch (Kodak Gallery)
       It was a lot of fun, even though the launch was scrubbed 5 minutes before launch at 2:15 AM February 4, 2009. These photos were taken by my PTSOS partner, Dan Burns, who teaches at Los Gatos High School. Dan has a 15 MegaPixel camera which is incredible. The two-stage Delta II rocket successfully launched its NOAA-N Prime weather satellite payload into space a few days later.

Impulse and Change in Momentum
       "Why do trains have loose couplers? Because if they didn't trains like this would never move--the engines could never generate enough motive power to pull 300 cars. The loose couplers help change the momentum of the train incrementally rather than all at once. Instead, the locomotives pull one (or maybe a few) car at a time, which in turn pull on the next ones, and so on until the entire train is moving along . . . then the train moves a bit faster, pulling on the cars at the front of the train, which in turn pull on the cars behind them . . . get the idea now? Modern locomotives such as the one pulling this freight train generate as much as 5000 horsepower each--as much as that is, not nearly powerful enough to move an entire train of this size at one time--hence loose couplers!