4 amazing skateboards in one nice lot. 1. 1990's Tony Hawk Conplete Skateboard, original falcon 3 design. With Rekon trucks and firelite classic wheels. 2. Sk8mafia Lucero deck. Signed by John Lucero. Brand new deck. 3. 1031 deck signed by entire team on a brand new creepy crawl deck. 4. Brand new super rare Big Mess deck with Blast design. This deck is extremely rare and is a must have for any collector. Both the signed decks are personalized to a guy named Jason that owned a skate shop here in Grant's Pass Or. Those guys were on his wall for a long time before he went out of business. If you have any questions or concerns please let me know. Thanks for looking. Steve
It's a neat piece of science art, and it also tells us something interesting. The arrows show us that the force on the skateboard is constantly changing, both in magnitude as well as in direction. Now the force of gravity obviously isn't changing, so the reason that these force arrows are shrinking and growing and tumbling around is that the skater is changing how their feet pushes and pulls against the board. By applying a variable force that changes both in strength and direction, they're steering the board.
To summarize, a skateboarder's feet need to do two things successfully to complete an ollie. They need to provide a changing force to move the board correctly (so that the combined force of gravity and the skater's feet add up to the green arrows above), and they need to provide different amounts of force with each foot (shown by the red and blue arrows above) to steer and turn the board into the right orientation.