Middle School STEM Sprint • Elastic Energy & Projectile Mechanics Single-Page Rapid Challenge Handout
− Tape Confiscated (Mechanical joints only!) RESTRICTED
Modify your launch angle θ to generate a higher parabolic arc that clears the 25 cm obstacle while generating enough kinetic velocity to reach the elevated 2.5m platform.
Pacing: 4 Min Redesign • 2 Min Official Trials
Phase 2 Redesign Blueprint (Higher Arc & Tape-Free Joint Solution) Barrier: 25cm • Target: 2.5m (+20cm High)
↑ Launcher Base ↑ 25cm Obstacle ↑ Elevated 2.5m Target
| Phase 2 Attempt | Cleared Barrier? | Zone Hit (Bullseye=50 / Inner=30 / Outer=15) | Points |
|---|---|---|---|
| Shot 1 (Redesign) | |||
| Shot 2 (Redesign) | |||
| Shot 3 (Redesign) |
Phase 1 Score
Phase 2 Score
GRAND TOTAL SCORE
Design Iteration Analysis
How did you adapt your launcher structure to remain rigid once tape was removed?
What specific angle adjustment enabled your projectile to clear the barrier and still hit the elevated target?
Sprint Part 2 of 2 • Iteration & Constraint Adaptation Middle School STEM Rapid Engineering
Drinking Straw (Fuselage) 1 STRAW ONLY
Cardstock Strip (Cut your own loops) 1 STRIP ONLY
Paper Clip (Ballast) 1 CLIP ONLY
Tape Allowance 8 CM MAX
With only 1 strip, you must cut it efficiently to create both front and rear loops. Optimize your lift-to-drag ratio and carefully position the 1 ballast clip to balance your center of gravity.
Sprint: 4 Min Build • 2 Min Official Launches
Phase 2 Strip Cutting & Assembly Blueprint (How will you divide the single cardstock strip?) Single Strip Division • CG Trim
Cut 1: Front Loop (1/3) Cut 2: Rear Loop (2/3) 1 Ballast Clip Placement
| Phase 2 Attempt | Distance (m) | Comparison to Phase 1 Best | Flight Stability |
|---|---|---|---|
| Flight 1 (Rationed) | |||
| Flight 2 (Rationed) | |||
| Flight 3 (Rationed) |
Phase 1 Best Distance
____ m
Phase 2 Best Distance
____ m
MATERIAL EFFICIENCY DELTA
Aeronautical Reflection
How did reducing the glider's mass affect its glide stability vs glide distance?
Why was the ratio of front loop size to rear loop size critical when you only had one strip?
Sprint Part 2 of 2 • Material Efficiency & Optimization Middle School STEM Rapid Engineering
Friction Corrugation: Lightly accordion-fold track floors to shed kinetic energy.
Double the Time: Aim for 8.0+ seconds on the heavy descent!
Teams have 6 minutes to redesign and iterate before the final trial runs! Can your track hold the steel sphere?
Maximum Points Win
Transit Time
× 10
10 points per full second in continuous motion
Target Catch
+ 25
Sphere finishes and stays inside the floor cup
Material Bonus
+ 5
Per unused full straw, card, or stick
Stall Penalty
− 15
Per manual rescue or stall longer than 1.0s
Score = (Time × 10) + Catch + Unused − Penalties
Record on your Official Handout
Group Discussion
Question 1: Friction vs Stalling
What was the exact boundary where adding friction caused the marble to stall completely? How did you calibrate your slope angles?
Question 2: Heavy Momentum in Phase 2
How did doubling the sphere's mass change the banking and structural rigidity required at your switchback turns?
Complete Section 3 on your handout before submitting Next: Awarding the Master Decelerator Trophy!
1. Heavy Steel Ball Higher mass = more inertia. Flattens weak paper tracks.
2. Mandatory 90° Turn Track must turn lateral to desk; requires banked sidewalls.
3. Tape Ration Confiscation Remove 15 cm of tape. Forces interlocking folded tabs.
Failure Mode A: The Dead Stall (>1.0s stop)
Coaching Question: "Where did your slope dip below the angle of static friction? What if you crease the center line slightly to reduce contact surface?"
Failure Mode B: The Corner Blowout (Fly-off at turn)
Coaching Question: "Why did the steel ball jump off the track at the turn? How do NASCAR tracks or roller coasters use banked curves to redirect centripetal acceleration?"
Failure Mode C: Structural Sag / Buckling
Coaching Question: "How can you use your two wooden craft sticks as truss braces beneath the longest span?"
Scoring Formula: Total = (Transit Sec × 10) + Catch (25) + Unused (5) − Stalls (15) Example: 7.2s run + Cup Catch (25) + 1 unused straw (5) = 102 pts.
Adjudication Criteria:
Key Concept: Kinetic energy is proportional to mass and velocity squared (\(KE = \frac{1}{2}mv^2\)). In Phase 2, the steel ball's higher mass produced greater momentum (\(p = mv\)), requiring deeper banked curves and sturdier structural triangulation to absorb energy without collapsing or stalling.
Gravity Brake Facilitation Guide • Middle School STEM Page 2 of 2 • Redesign & Debrief Protocol
15° Incline • Steel Cargo
Mission Pivot
1. The 15° Incline: The far string anchor is raised 1.0m to create an uphill slope.
2. Cargo Added: 2 steel washers are taped to your straw carriage.
3. High-Torque Pivot: +1 rubber band is added to your kit to build a dual-band parallel motor!
+ 2 Steel Washers (Cargo) ATTACHED
+ 1 Extra Rubber Band DUAL MOTOR
Track Geometry 15° UPHILL
Climbing against gravity requires maximum rotational torque. Linking two rubber bands in parallel doubles spring tension, while curving your blades deeper increases static thrust!
Pacing: 5 Min Redesign • 2 Min Incline Trials
Phase 2 High-Torque Redesign (Blade pitch angle θ & dual parallel rubber bands) Symmetrical Washer Cargo Balance
↑ Increased Blade Pitch Parallel Dual-Band Motor Cargo Washer Balance ↑
| Incline Trial | Winds | Distance Climbed (m / 4.0m) | Summit Reached? | Incline Points |
|---|---|---|---|---|
| Incline Test 1 | Practice | |||
| OFFICIAL SUMMIT HAUL |
Phase 1 Speed (m/s × 20)
Phase 2 Incline (Dist × 15 + Summit 30)
GRAND TOTAL SCORE
Aerodynamic & Mechanical Analysis
How did twisting the rubber band more tightly increase RPM vs risking driveshaft friction?
Did the dual-band parallel configuration provide more torque to climb the uphill slope? Explain why:
Propeller Racer Lab Sheet • Lab Part 2 of 2 Middle School STEM Rapid Engineering
Parallel Motor: Link two rubber bands side-by-side to double your torque!
Blade Pitch: Increase blade curvature to generate higher static thrust off the launch line.
Cargo Balance: Tape washers symmetrically to prevent the straw from pinching the string.
Teams have 6 minutes to modify motor torque before official incline trials! Can your engine reach the summit?
Maximum Points Win
Phase 1 Speed
× 20
20 pts per meter/sec on horizontal 4.0m line
Phase 2 Distance
× 15
15 pts per meter climbed up the 15° incline
Summit Bonus
+ 30
Completed full 4.0m climb to top anchor
Derail / Assist
− 10
Per manual push or string binding restart
Total Score = (Speed × 20) + (Climb × 15) + Summit − Assists
Record on your Lab Sheet
Group Discussion
Question 1: Torque vs High RPM
Why did a high-speed racer from Phase 1 stall on the Phase 2 incline? How did adding a parallel rubber band alter mechanical torque?
Question 2: Propeller Blade Pitch θ
If your propeller blades were bent too flat, what happened? If they were bent too steep, why did the motor struggle to spin?
Complete the analysis questions on Page 2 of your Lab Sheet Next: Announcing the Master Aero-Engine Champion!
Advanced Modification
Torque & Incline Protocol
Incline Pivot
Announce to the class: "The test track is no longer flat! The destination anchor has been raised by 1.0 meter (creating a 15° climb). In addition, your racer must carry 2 heavy steel washers without stalling midway!"
1. 15° String Incline Gravity opposes thrust. Requires higher static torque to move.
2. Dual-Washer Cargo Taped symmetrically to straw to keep carriage balanced.
3. +1 Rubber Band (Bonus) Allows parallel double-band motor for 2x torque delivery.
Symptom A: Propeller spins furiously, but racer doesn't move forward
Coaching Question: "Check your blade pitch and spin direction! Are your blades pushing air toward the front or rear? If blades are flat, they cut air without producing thrust."
Symptom B: Propeller binds and stops after 2 turns
Coaching Question: "Where is the driveshaft rubbing against the wooden chassis? Is your bead bearing in place? Add a tiny drop of graphite/oil or loosen shaft tension."
Symptom C: Chassis tilts sideways and pinches the string line
Coaching Question: "Is your center of mass hanging directly beneath the straw? Re-center the cargo washers so gravity stabilizes the carriage."
Scoring Formula: Total = (Speed × 20) + (Climb Dist × 15) + Summit (30) − Assists (10) Example: 2.0 m/s (40) + 4.0m climb (60) + Summit (30) = 130 pts.
Adjudication Criteria:
Key Concept: Energy conservation dictates \(PE_{\text{elastic}} \rightarrow KE_{\text{rotational}} \rightarrow KE_{\text{linear}} + \text{Thermal Friction}\). In Phase 2, climbing requires mechanical work against gravity (\(W = mgh\)). Linking rubber bands in parallel doubles spring constant (\(k_{\text{eff}} = k_1 + k_2\)), doubling torque output to overcome the incline gravitational component (\(F_g = mg \sin\theta\)).
Propeller Racer Facilitation Guide • Middle School STEM Page 2 of 2 • Incline Redesign & Assessment Protocol
Phase 2: Slick Track & Heavy Cargo Redesign
Slick Ice Zone • Steel Cargo
Constraint Shift
1. Slick Ice Track: A 1.0-meter wax paper / plastic film zone is taped over the runway just before the dock (\(\mu\) reduced by 60%!).
2. Heavy Cargo: 2 steel washers must be secured inside your harness.
3. Bonus Item: 1 latex balloon is provided to engineer an air-drag parachute or brake bladder!
+ 2 Steel Cargo Washers IN HARNESS
+ 1 Balloon (Air Drag Parachute) NEW ITEM
Runway Surface 1.0M SLICK ZONE
With low surface friction (\(\mu\)), ground pads lose stopping power. Combine mechanical wheel clamping with an aerodynamic drag parachute/flap to stop the heavier vehicle before the overshoot hazard line!
Pacing: 5 Min Redesign • 2 Min Competition Runs
Phase 2 Redesign Blueprint (Dual-Action Braking: Aerodynamic Drag + Wheel Caliper) Slick Zone Traversal • Cargo Retention
↑ Balloon Air Flap Slick Track Caliper Pad Washer Retention ↑
| Phase 2 Attempt | Mount Time (≤15s?) | Stopping Distance (cm) | Overshoot Hazard? | Points |
|---|---|---|---|---|
| Slick Test 1 | Practice | |||
| OFFICIAL SLICK RUN |
Phase 1 Dock Score
Phase 2 Slick Score
GRAND TOTAL SCORE
Friction & Modular Design Analysis
Why was designing a quick-mount slip-on harness better engineering than permanently taping the car?
How did aerodynamic drag (air-brake) compensate for lost floor friction (\(\mu\)) on the slick track?
Matchbox Precision Dock • Standardized Fleet Lab 2 of 2 Middle School STEM Rapid Engineering
Cargo Retention: Your harness must secure the washers so they don't slide off during deceleration!
Teams have 6 minutes to redesign and iterate before final Pit Lane runs! Can your brakes stop the heavy car on ice?
Maximum Points Win
Phase 1 Dock
50 pts
Bullseye stop at 200 cm (30 pts for Bay)
Phase 2 Slick Dock
60 pts
Stopping heavy car inside the target dock
Quick Pit Bonus
+ 15
Harness mounted & unmounted in <15 seconds
Overshoot Crash
− 20
Per crash beyond the 225 cm hazard line
Total Score = Phase 1 Dock + Phase 2 Slick + Quick Pit − Crashes
Record on your Lab Sheet
Group Discussion
Question 1: Stopping Distance Physics
When the runway became slick (\(\mu\) decreased) and cargo mass doubled, why did braking distance increase exponentially (\(d = \frac{v^2}{2\mu g}\))?
Question 2: Modular Engineering
Why was building a quick-mount clip-on harness better engineering than permanently taping the car? How does this reflect real-world vehicle testing?
Complete the reflection questions on your handout Next: Awarding the Master Braking Engineer Trophy!
Advanced Modification
Low-Friction Protocol
Friction Drop
Announce to the class: "An icy weather front hit the runway! A 1-meter slick film has been taped before the docking bay, reducing floor friction by 60%. Furthermore, your car must haul 2 heavy steel washers without overshooting the hazard line!"
1. Slick Ice Zone 1.0m wax paper / smooth plastic film taped between 100cm–200cm.
2. Dual-Washer Cargo 2 heavy washers placed in harness (+16g mass = 2x momentum).
3. +1 Balloon Added Allows aerodynamic drag chute or inflated friction bumper.
Symptom A: Brakes engage immediately on the ramp and stop car dead at the foot
Coaching Question: "How can you delay the brake engagement? Can you use a flexible trailing straw or paper skid that only presses down once the car levels out on the flat floor?"
Symptom B: Car spins out or veers off the runway
Coaching Question: "Is your braking friction symmetrical? If one side has more drag than the other, torque causes the vehicle to pivot. Balance your brake pads!"
Symptom C: Skids slide straight through the slick zone into the hazard wall
Coaching Question: "Why did ground friction fail on the wax paper? Can you inflate or shape your balloon into an aerodynamic air-brake flap that doesn't rely on floor friction?"
Scoring Breakdown: Total = Phase 1 Dock + Phase 2 Slick + Quick Pit (15) − Crashes (20) Bullseye: 50 pts | Dock Bay: 30 pts | Stop: 10 pts | Overshoot Crash: 0 pts.
Pit Lane Adjudication:
Key Concept: Stopping distance is derived from the work-energy theorem: \(\frac{1}{2}mv^2 = F_f \cdot d = \mu mg \cdot d \implies d = \frac{v^2}{2\mu g}\). On a dry floor, mass \(m\) cancels out for pure sliding friction; however, in Phase 2 on the slick track, \(\mu\) dropped significantly, requiring supplemental aerodynamic drag force (\(F_D = \frac{1}{2}\rho v^2 C_D A\)) via the balloon flap to absorb momentum without wheel lockup.
Matchbox Precision Dock Facilitation Guide • Middle School STEM Page 2 of 2 • Slick Track Redesign & Assessment Protocol
