Shake & Fall: Engineering the Drop
Welcome to Day 2. Today you become an engineer.
Three challenges. Three failures. Three fixes. By the end of the day you'll have protected a fall, channeled a fall, and survived a fall — three different problems with three different solutions. Same world. Different physics.
No experience required. Build, test, break, fix, try again.
You live in earthquake country, on the edge of one of the largest agricultural valleys on Earth. Both of those facts mean engineers built this place — and they had to think about things falling in three different ways:
- Make things fall on purpose. Almond harvest grips a tree trunk with a machine and shakes it until every nut drops. Same for walnuts.
- Channel how things fall. The nuts ride conveyors and chutes through processing plants. Marbles falling through tubes are basically the same physics.
- Keep things from falling. Grain silos, dairy barns, water tanks — every tall structure in Gustine has to survive the next earthquake.
- Water Drop (right now) — protect a cup of water dropped from height
- Marble Run (morning) — design a roller coaster from foam pipe
- Earthquake-Proof Tower (afternoon) — build a tower that survives a quake
When wildfires cut off mountain communities, when floods isolate farms, supplies come from above. The drop has to be soft enough to not destroy what's inside. That's your warm-up.
Materials per team: 1 small cup (3 oz), 1 manila folder, ~5 sheets paper, ~3 ft masking tape, ~6 paper clips, ~3 ft string, 3 drinking straws. Shared: water + syringe at the front.
Three ways to soften a drop — combine two:
- Slow the fall (paper parachute, streamers, wide fins)
- Cushion the impact (paper padding, crumpled folder)
- Seal the cargo (a paper-and-tape lid with a tiny hole)
Build fast. You have 10 minutes to build, 5 to drop. One drop only. Measure the mL remaining after impact.
When fires rip through the Sierras, CAL FIRE air tankers drop fire retardant. When floods cut off rural farms, ag aviation pilots from Modesto and Turlock drop supplies. Every drop is engineered: cargo weight, drop height, wind correction, chute size. The job is payload engineer.
You just made something fall safely. Now you'll make something fall on purpose, in a path you design, and keep it moving the whole way.
A roller coaster is the cleanest example of potential energy turning into kinetic energy. Height at the top equals speed at the bottom. Friction steals energy on every turn. Build too gentle and your marble stalls. Build too steep and your marble flies off the track.
These two videos give you (1) the physics behind why a roller coaster works, and (2) what a foam-pipe-and-marble build actually looks like in practice.
- At least one loop
- At least one turn (90° or more)
- At least one jump (a gap the marble flies across)
- ~6 ft of foam pipe insulation, pre-cut in half lengthwise (each piece gives 2 channels of track)
- 3 marbles (standard size)
- 1 roll of masking tape
- Scissors
- 2 paper labels (for Max PE and Max KE — use later)
- Anchors of opportunity: chairs, tables, doorframes, walls
Before you tape anything, sketch your full coaster on your Build Log. Mark:
- Where the marble starts (highest point)
- Where the loop goes
- Where the turn happens
- Where the jump is and where the marble lands
- Where the marble ends up (lowest point)
Pro tip: the loop is the hardest feature. The marble needs enough speed entering the loop to make it all the way around. If your loop is at the very start of the track, your marble won't have built up speed yet. Most working coasters put the loop one-third of the way down, after a steep first drop.
- Anchor the start high. Tape your foam pipe to the back of a chair, a doorknob, or a table edge. Higher = faster marble. Aim for at least 3–4 feet up.
- Lay the track downhill. Use the natural curve of the foam pipe. Tape it every 2–3 feet so it doesn't shift.
- Build the loop. Make a circle with the pipe and tape it to itself where the loop closes. Test the loop alone before connecting it — drop a marble into the top and make sure it makes it all the way around.
- Connect everything. Where two pipe sections meet, overlap them an inch and tape generously. Loose joints are where marbles fall off.
- Build the jump last. Cut a 2–4 inch gap in the track. The marble has to fly across it and land back in the channel. Align the landing pipe slightly lower than the launching pipe.
Short break. Leave your coaster up — we're going right back to it.
10:45 – 11:00Your coaster either works or doesn't. Most don't on the first run. Engineering is what happens next.
Drop your marble at the start. Watch closely. Where does it fall off?
- Marble stalls before the loop → not enough starting height. Raise the start.
- Marble flies off the loop → too much speed. Add a curve before the loop, or shrink the loop.
- Marble overshoots the jump → narrow the gap, lower the launch angle.
- Marble undershoots the jump → close the gap or steepen the launch.
- Marble jumps the channel on turns → loose tape. Re-tape the outside of the curve.
Change one thing, then test. Don't redesign your whole coaster — find the one weakest part and fix it. Run the marble again. Note what changed.
Iterate until your marble completes the entire course — loop, turn, jump, finish — without falling off. Three clean runs in a row is "done."
If you finish early and your coaster is rock solid, add a corkscrew, a second loop, or a longer track. Builder's choice.
Once your marble runs the full course, tape your two labels onto the coaster:
- Max PE (maximum potential energy) — the highest point on your track. The marble is moving slowest here.
- Max KE (maximum kinetic energy) — the lowest point, or the point right after the loop. The marble is moving fastest here.
Record a video of your marble completing the entire course. One full clean run, start to finish. You'll share this at the end of the day.
A roller coaster designer at Six Flags, Disneyland, or Bolliger & Mabillard does exactly what you just did, with more math. They calculate the first drop's height so the train has just enough energy to clear the loop without flying off. The same physics runs the conveyors inside every almond processing plant in the Central Valley — Blue Diamond in Salida, Monte Vista Farming in Denair — they all move nuts by gravity through engineered channels. The job is mechanical process engineer. Two-year degrees at Modesto JC or Merced College get you in the door.
Lunch break. Leave your coaster up — we'll do final demos at the end of the day.
12:00 – 1:00The morning was about engineered falling. This is about engineered not falling.
Gustine sits in earthquake country. The Hayward, Calaveras, and San Andreas faults are all within driving distance. Every building in California is required by code to survive a major quake — which is harder than it sounds, because earthquakes don't push down on a building. They shake it sideways. Buildings are usually only strong in one direction.
- ~60 gumdrops (joints)
- ~100 toothpicks (struts)
- 1 cardboard square (~12 × 12 in) for the base
- Ruler
Three things matter for earthquake-resistant towers:
- Wide base. A wide footprint resists side-to-side shaking. Narrow base = topple.
- Triangles, not squares. A triangle holds its shape under stress. A square folds into a rhombus. Cross-brace with diagonals.
- Tapered top. Heavy at the top = more lever to topple. Narrow your tower as it rises.
Sketch your tower from the side AND from above. Mark every triangle.
- Start with the base layer on the cardboard. Push toothpicks into gumdrops to form your first footprint. Triangles are more stable than squares. The cardboard is your "ground" for the shake test — don't tape your tower to it; gravity should hold it down.
- Build up in stable units. Each layer should be triangulated. Don't just stack squares.
- Cross-brace as you go. Add diagonal toothpicks between corners. This is where earthquake resistance lives.
- Don't go too tall too fast. A 20 cm tower that survives the quake beats a 40 cm tower that collapses. Stop and pre-test (gently tilt the cardboard) every 10 cm of height.
Bring your tower (still on its cardboard base) to the testing station. Your facilitator (or a designated "ground crew" student) will grip the cardboard base on both sides and shake it side-to-side for 15 seconds — steady, rhythmic, like a metronome. Not gentle, not violent. Same motion for every team so the test is fair.
Watch what happens. Where does your tower flex? Where does it stay rigid? Does it lean and recover, or lean and fall?
- Survived intact — tower still standing, no broken joints
- Wobbled but stood — tower leans but still standing
- Partial collapse — top sections fell, base still standing
- Total collapse — tower on the cardboard
Competition: tallest tower that survives intact wins the day.
Review what failed (or what almost did). Make one targeted change to your tower — add cross-bracing where it bent, widen a narrow point, lower a top-heavy section.
Shake-test again. Same motion. Did your fix work?
Record a video of your best trial — surviving the quake intact. This is your tower's certification.
Structural engineers in California don't just design buildings — they design buildings that survive earthquakes. Caltrans engineers retrofitted every major freeway overpass after Loma Prieta and Northridge. PG&E employs engineers who inspect every dam, transformer, and gas pipeline for earthquake risk. The biggest shake table in the world is at UC San Diego — engineers from all over the world test full-size buildings there before construction. Structural engineering is a 4-year degree (UC Davis, UC Berkeley, Cal Poly SLO, Cal State Fresno). Starting pay in California: $75–95k.
Three challenges, three different problems, one set of skills. You sketched, built, tested, failed, fixed, retested. That's the engineering loop. Real engineers do it 100 times a day. You did it three times today.
Each team picks one — your best coaster run OR your earthquake-surviving tower. Show the room. One sentence on what made it work, one sentence on what you'd change with another hour.
On your 📋 Build Log, finish these three:
- The hardest thing to get right today was…
- One thing I learned that I didn't know this morning:
- If I had one more hour, I'd rebuild…
Day 2 in the books. You engineered a soft landing, a controlled fall, and a structure strong enough to survive an earthquake. See you next week for Mini-Med School.