Designing a Curve

Introduction

The Scenario You've just been hired as a junior civil engineer. Your team has been asked to design a curved section of highway that's had one too many accidents in bad weather. By the end, your team needs an answer to three things: how sharp this curve can safely be, what speed to post on the sign, and whether that changes when it rains. You'll have to defend your recommendation with physics — not just hand over a number. But before any of that, you need to understand something more basic: what actually happens to a car — and the people inside it — as it goes around a curve? Watch the two videos below before you go any further. [Video 1 — the road curve itself: establishes the real curve your team is working with] [Video 2 — dashboard footage: driving in a straight line at different speeds, then around a circular path at different speeds] Don't take notes yet. Just watch. Step 1 — Observe Watch both videos again, and this time, pay attention to what you notice — not what you already know from a physics class. What was different between driving in a straight line and driving through the curve? From your own experience in driving or riding, would there be a moment you'd describe as feeling "pushed" in some direction? When, exactly? Did that feeling change when the car sped up or slowed down through the curve? Is there anything visible in the video — something swinging, sliding, or shifting — that shows something happening, even in a moment where you personally wouldn't have noticed it? Before you move on: write down at least two questions this raised for you. Not answers — questions. What do you actually want to know about what's going on here? (The rest of the activity — and seven more like it in the full Mechanics, Motion and Energy Exploration — picks up from here.)