Gravity Vehicle San Diego Regional

The Goal Build a ramp and a vehicle powered solely by its own gravitational potential energy to reach a target as quickly and accurately as possible.

Vehicle Parameters Vehicle Mass: <=2.0 kg No electric or electronic components Must move as a whole – no tethers, anchors, etc. Only wheels may touch the track No size limit for vehicle alone – however, in ready-to-run, vehicle and ramp must be no more than 50.0 cm x 50.0 cm long x 100.0 cm high

Vehicle Dowel >= 20cm <= 1cm <= 0.5cm ~¼” round wood within 1.0 cm of floor at least 20.0 cm above floor <= 0.5 cm in front of dowel except wheel >= 20cm <= 1cm <= 0.5cm

Brakes Distance precision depends on brakes. Common Types: String Wingnut

Ramp Shape: Build frame with the shape you want, attach a thin sheet Flat - Easy to build Curved - smoother transition Build frame with the shape you want, attach a thin sheet Materials 1/8” MDF Sheet Metal Ease transition to floor to reduce error Don’t let dowel scrape floor

Release Mechanism Launch using unsharpened #2 pencil Ideas: May be a part of release mechanism May extend beyond dimension limits Ideas: Drill hole in Ramp, “hang” Vehicle from pencil. Pull out pencil to release. Cut hole in Ramp, use some other kind of mechanism. Place release mechanism at top of Ramp (no holes required).

Adding Mass Added mass helps overcome friction Height of added mass raises vehicle center of mass => higher potential energy

Examples

Vehicle Distance from Target Additional Parameter(s) Practice Log At least 4 parameters At least 10 runs Target Distance Vehicle Distance from Target Run time Additional Parameter(s) FIXED Target Distance Vehicle Distance from Target Run Time SELECTED # axle turns Alignment

Track Smooth, level, and hard surface Start Line Timed Target Point 1.00m 9.00 – 12.00m 0.50m Line 8.50m Line Smooth, level, and hard surface Lines and points are marked with/on 1” tape Distance between 9 and 12 meters Regionals: 0.50 meter increments State: 0.25 meter increments Nationals: 0.05 meter increments

The Competition 8 minutes to setup for and start 2 runs No electric tools except calculator Remove alignment or targeting devices before run Must not touch/push vehicle or ramp when launching

Scoring The Run Score for each run: 2 pts./cm x Vehicle Distance + 1 pt./sec x Run Time + Penalties Vehicle Distance is point-to-point Accuracy emphasized over speed. Only go as fast as you can brake accurately.

Scoring – Issues Failed Run Vehicle moves but does not pass the 0.50 m Timing Line Time or Distance not measurable Not started within 8 minutes Crosses 0.5 m line, but not 8.5 m line => Time = 60 seconds Non-Run If the Vehicle does NOT move, not counted as a Failed Run. May try again Incomplete Practice Log = 250 point penalty No Practice Log = 500 point penalty

Scoring – Tiers 1: A clean run. No violations 2: Competition violation 3: Construction violation 4: Two failed runs 5: Failure to impound

Venue Miramar USD – Not announced Student Services Lunch Area (tentative) USD – Not announced

Suggestions Build slightly less than maximum size & weight Practice on different types of floors Clean the floors Axle bearings reduce friction Dowels are the most frequent construction violation Be careful not to accidentally triggering release

Resources Problem Solving / Technology CD Gravity Vehicle Digital DVD www.soinc.org/gravity-vehicle www.soinc.org/events/rules-clarifications scilympiad.com/san-diego-so/QnAs scioly.org/forums/viewforum.php?f=315