Design a cushion that lowers collision force

How can a package reduce average force while stopping the same object?

Submit: An evidence record, explanation and revision.

Related lesson: Forces and Momentum

This is a teacher-led extension beyond the short lesson. The task supplies a performance opportunity; completion alone does not certify mastery, full NGSS coverage or state alignment.

Build the idea

Impulse equals change in momentum. For the same momentum change, increasing stopping time reduces the magnitude of average force: F_avg = Δp/Δt. Peak force can differ from average force. A cushion must also fit size and material constraints and avoid bottoming out.

Evidence and model inputs

Invented sensor records for a 0.20 kg model payload slowing from 2.0 m/s to rest without rebound: cushion A stops it in 0.010 s, B in 0.040 s. Both changes have magnitude Δp=0.40 kg·m/s. Build a low-energy model package for a soft payload; do not assume measured contact time from an ordinary stopwatch.

Keep actual observations, published findings and invented model cases labeled separately. If a source or required equipment is unavailable, pause that part with a teacher; do not invent results.

Materials and preparation

Soft small payload, paper or foam packing, ruler, tray and optional suitably resolving video or sensor.

Grade-level scope

Low-energy classroom models only. No people, raw eggs, high drops or testing of protective equipment on bodies.

Do the work

1. Calculate average force magnitudes for A and B and distinguish the supplied sensor data from your own model tests.
2. Set constraints: maximum 5 cm cushioning thickness and only the teacher-provided reusable materials.
3. Build two packages for the same soft payload; use the same low, teacher-approved release height and clear test tray.
4. Record damage or deformation over repeated trials; use suitable slow-motion or sensors only if they resolve contact time.
5. Improve one design and explain which observations support reduced force and which remain indirect proxies.

Learner worksheet

Write on paper or type here and print. Entries stay in this page’s memory and are lost when you leave or reload; they are not saved or submitted.

Check your reasoning

1. What are the modeled average forces?
2. Why keep payload and release conditions fixed?
3. Is average force the maximum force?
4. Can less visible damage alone give a force in newtons?

Teacher review guide

Review the actual deliverable and discuss the reasoning. For each criterion, use 0 when evidence is absent or fundamentally incorrect, 1 when partly supported with a material error or omission, and 2 when accurate, supported and complete for the stated task. Maximum 8 points is a task score, not a proficiency certification. Give feedback and allow revision.

1. Applies impulse with correct units and assumptions.
2. Builds within explicit constraints.
3. Conducts matched repeated tests and a revision.
4. Links stopping time to force while distinguishing proxies.

Sources and standard reference

• Official NGSS HS-PS2-3 performance expectation — inspect the practice, core idea, crosscutting concept and assessment boundary.

Instructional text and hypothetical cases are original. Linked source readings supply published evidence where specified. Teachers should judge fit with their course and state requirements.