Lesson 2: Friction and Alignment
Duration of Days: 2.5
Lesson Objective
Students will build a low-friction chassis and apply Newton’s First Law to ensure their car remains in motion as long as possible.
1. Why does the car stop even after the balloon is empty?
2. How does axle alignment affect the amount of force needed to start the car?
Newton’s First Law, Inertia, Static Friction, Rolling Friction, Alignment.
CTE PS 8: Construct and analyze a prototype. ENG.06.01: Use math/science to solve engineering problems.
Students construct the body and wheel system. They must troubleshoot "wobbly" wheels and ensure axles are parallel. They perform a "Coast Test" to see how far the car rolls with a single push.
Purpose: To minimize the forces of friction that oppose the balloon's thrust.
DOK Level: Level 3 (Strategic Thinking).
Use "Axle Jigs" (pre-cut templates) for students who struggle with spatial alignment to ensure their wheels are straight.
The "One-Finger Push" test. If the car curves or stops immediately, the student must identify which type of friction is the culprit.
Materials: Cardboard, plastic bottle caps/CDs, skewers (axles), straws (bearings), hot glue.