Physics · Unit 1: Kinematics ·  Problem 1-3-1

Crosswalk Safety Study

🚧 PROBLEM

The district wants a crosswalk near a blind curve by the gym. Given reaction-time and stopping-distance data, you decide where it should go and what the speed limit should be — and defend it in a one-page memo to the district  ·  3 class days

Synthesizingall of Unit 1 — vocabulary, graphs, and equations

🧭 Problem Summary

This is not a project with a target to match — there's no answer key. The district has a real decision to make: where exactly should a new crosswalk go near the blind curve by the gym, and what speed limit should be posted on that stretch of road? You'll be given reaction-time ranges and stopping-distance data, and it's on you to turn that into a specific, defensible recommendation.

Two reasonable people could look at the same data and land on different — both defensible — answers, depending on which assumptions they choose (whose reaction time to design for, what safety margin is enough, whether to plan for wet pavement). Your job isn't to find "the" answer. It's to make a choice, show your work, and argue for it like someone's actual safety depends on it — because in a real version of this problem, it would.

The three days

1Read the scenario and data, and pin down which assumptions you're making.
2Run the stopping-distance calculations for multiple speed limit options.
3Draft, refine, and finalize your one-page memo.

Why it matters

Every skill from this unit shows up here at once, with no scaffolding telling you which one to reach for: distance and displacement vocabulary, reading and building graphs, the kinematic equations, and the missing-variable strategy. This is the moment the unit has been building toward — using physics to make an actual decision, not just to get a numeric answer.

🧩 Before You Start — Prerequisite Check

This problem draws on everything in Unit 1. Check yourself honestly — if something's shaky, the review links in the sidebar are exactly what they're there for.