The 42nd Period | STEM Education Hub

Pick a real ride — a bike computer log, a car's dashboard footage, or a rollercoaster POV video with a speed readout. From here forward, that data is the whole assignment: your job is to reconstruct exactly what happened, one segment at a time, and then say what should happen next.

🎯 Goals

Turn a messy real velocity record into a clean, organized v-t table.
Identify stretches where treating acceleration as constant is a reasonable approximation.
Calculate acceleration and displacement for every segment, and track a running total.
Use a segment's velocity and acceleration to forecast what happens several seconds further.
Write up your method clearly enough that someone else could reproduce your numbers.

🧰 Materials

📱Your data source: a bike computer/GPS log, a car's dashboard video, or a rollercoaster POV clip with a speed overlay

⏱️Stopwatch or video scrubbing tool, if you're extracting readings from a video

📐Graph paper or grid handout

🧮Calculator

📓Physics notebook

DAY 1

Organize the Data

Section 1 of 5

Choose and Clean Your Data Source

Pick a real velocity record — from your own device, a video, or a teacher-provided option.

Confirm with your teacher that your source has enough variation (speeding up, slowing down, or holding steady) to be worth analyzing.

Extract velocity readings at regular time intervals and build a v-t table.

If you're pulling data from a video, pause it every few seconds and record the speedometer reading and the timestamp. Consistency matters more than density — 6 good readings beat 20 sloppy ones.

⚠️ Real data has noise. Round to a sensible precision rather than copying down every jittery digit the display shows.

Section 2 of 5

Identify Constant-Acceleration Segments

Sketch a rough v-t graph of your data and mark where the slope changes noticeably.

Each relatively straight stretch between those marks is one segment you'll analyze separately.

Decide, honestly, where treating a segment as constant acceleration is reasonable — and where it isn't.

A segment with a lot of jitter or a clearly curving trend is a place to note as a limitation in your write-up, not force into a straight line.

📓 Physics Notebook

Which segment of your data was hardest to treat as constant acceleration, and why? Write down your reasoning now — you'll need it for Day 3's write-up.

DAY 2

Calculate Acceleration and Displacement

Section 3 of 5

Build Your Calculation Table

Use the Ride Reconstructor below with your own data's waypoints.

Enter the (time, velocity) pairs at each segment boundary to generate acceleration, displacement, and a running total automatically.

Enter the (time, velocity) pairs from YOUR real data — every point where the ride's pace noticeably changes. This builds your calculation table live, segment by segment.

t (s)v (m/s)

Segment	Δt (s)	Δv (m/s)	a (m/s²)	Δx (m)	Running Δx (m)
0–5s	5	+8.0	1.60	20.0	20.0
5–12s	7	+0.0	0.00	56.0	76.0
12–18s	6	-5.0	-0.83	33.0	109.0

total displacement so far: 109.0 m

🔮 Forecast: What happens next?

Assuming the acceleration from your last segment continues, predict what happens after this many more seconds:

seconds

predicted velocity

-1.2 m/s

additional Δx

4.6 m

projected total Δx

113.6 m

This tool doesn't save your data — copy your table and forecast into your notebook before you write up your method.

Double-check at least two segments by hand.

Pick your two largest segments and verify the acceleration (Δv/Δt) and displacement (trapezoid area, or the matching kinematic equation) using pencil and paper — don't just trust the tool blindly.

DAY 3

Forecast and Write Up

Section 4 of 5

Make Your Forecast

Use your final segment's acceleration to predict velocity and position several seconds further.

The Ride Reconstructor's forecast section does this automatically — but state your assumption explicitly: you're assuming the last segment's acceleration keeps going.

Section 5 of 5

Write Your Method

Write a short explanation covering: your data source, how you built your table, which equations you used and why, and your forecast.

For each segment, name which of the four kinematic equations you used and which variable was missing — reference the strategy from Lesson 1-2-2 directly.

Be honest about the messiness.

Note any segment where constant acceleration was a rough approximation, and explain how that affects your confidence in that part of your answer.

📊 What Gets Graded

Method — correct equation choices, justified by the missing-variable strategy
Accuracy — calculations check out when verified by hand
Forecast — a clearly stated assumption and a calculation that follows from it
Write-up — someone else could follow your method without asking you questions

📤 Turn In

Your completed calculation table — every segment's acceleration, displacement, and running total
Your forecast, with the assumption you made stated explicitly
A short written explanation of your method

← Back to Project 1-2-3 OverviewNext up: Problem 1-3-1, Crosswalk Safety Study.