1. History & Physics of Skateboarding

3. Early Origins: Scooters
Crate Scooters
Began 1920s
Used roller skate wheels
Little to no ability to turn
Wood box or crate with handle

4. Early Origins
Other Modifications of standard roller skates – with metal wheels
Similar to a dolly

5. Skateboarding Demographics
2002: 18 million skateboarders worldwide
85% under the age of 18
74% Male

6. Parts of a Skateboard Wheels/Bearings Trucks (base plate & Cushions)
Deck (grip tape)
Accessories (rail guard, nose guard, tail guard)

7. The Truck

8. The Wheel

9. Popularity Skateboarding popularity has waxed and waned over the last several decades.
Popular: Late 1970s-mid 1980s Not Popular: Late 1980s to mid 1990s Popular : Late 1990s to 2003 Popularity Related to: Technologically changes in the board, cultural changes, and inventiveness of riding

10. History – Timeline of the Skateboard
1940s -1958: Southern California – Winter time surfers want to practice and created Skateboards. 1960s Clay Wheels 1973: Steerable truck Fiberglass, plastic & aluminum decks 1973: First Polyurethane wheel (open ball bearings) 1976: First Skate parks (200 skate parks by 1982) California drought –empty pools 1978: Sealed ball bearings 1979: Grip tape 1980s: Laminated wood for decks

11. History – Timeline of the Skateboard – The Moves
1950s: Street and sidewalk riding - practice surfing 1965: First Skateboard Competition 1970s: Freestyle & Street Slalom 1976: first skateboard parks : The First Vertical Revolution 1985: Age of the half -pipe 1992: 2nd Street Revolution 1995: The Second Vertical Revolution .

13. History – The Pioneers
Alan Gelfan Tony Alva Mike Mcgill Rodney Mullen Steve Caballero Tony Hawk

14. The 1980’s
Skaters made their own wooden ramps in their backyards to skate on. Street skating became more popular also. The Ollie: 80% Street tricks 60% Vertical tricks

15. 1990’s
The X-Games came out in the 1990s and made skateboarding even more popular. Large media coverage on skateboarding has moved it from an Skate parks have also gave boost to the skating community in many towns. The many different ramps, pipes and bowls present at these parks have led to a change in equipment.

16. Modern Types of Skateboards
Street: (small, hard wheels & small decks)
The wheel sizes are relatively small so that the boards are lighter, and the wheel's inertia is overcome quicker, thus making tricks more manageable.
Vertical:
Downhill: hard, large wheels, long decks
Luge:

17. Forces of Skateboarding
Use of forces: gravity, friction, momentum, rotational, and more – to complete a variety of moves
Gravity: Gives speed to the skater – related to slope
Friction: used by wheels to grip, grip tape to help hold rider to board, bearings lower friction in the wheels to increase speed

18. Forces of Skateboarding
Momentum: Linear Momentum allows riders to reach a high vertical height – Height increased by thrusting.
Flat part of a half-pipe allows for thrusting
Momentum: Rotational aka Angular Momentum. Control allows to complete of a variety of moves.

19. Physics of some moves
The 360 Angular momentum is conserved by controlling the arms – pulling them in makes you go faster.

20. Physics of some moves Vertical
Vertical riding is maintained by centrifugal force. Rider stays vertical due to the circular motion imparted on rider/board. “g-forces” both positive and negative are experience by the rider.
Heavy during vertical – weightless during the “air” portion of the ride.

22. Physics of some moves The Ollie
Distribution of weight quickly changes from the back of the board to the front.
Rebound (Newton’s Third Law) helps board and rider achieve altitude

23. Physics of some moves Luge & Downhill Riding
Large wheels – good for speed
High quality bearings for speed
Hardness of wheel varies
Decrease cross-sectional area to decrease air resistance. (ex. Luge – completely laying down.

24. The Ollie -Flat Press downward on front foot
Release front foot as the back foot kicks down.
Front foot controls the board through a parabolic path
First done by Rodney Mullen

26. Downhill Nightmares Wobbles caused by resonance
Resonance – the positive feedback loop of over compensation.
Loss of balance
Too much speed for a turn
Gravel/rock: sudden impact

29. Videos