Lesson 2: Friction and Axle Alignment
Duration of Days: 5.5
Lesson Objective
Students will construct a chassis and align axles to minimize rolling friction and ensure a straight flight path.
1. Why does a "wobbly" wheel stop a car faster than a heavy car?
2. How can we reduce the contact area between the axle and the frame?
Static Friction, Rolling Friction, Normal Force, Bearing, Co-efficient of Friction.
ENG.04.01: Identify and describe the properties of materials
Students build their basic frame (balsa or foam). They must use a square to ensure axles are 90° to the frame. They will test "dry" axles vs. axles lubricated with graphite
.
Purpose: To demonstrate that engineering precision is more important than raw power.
DOK Level: Level 3 (Strategic Thinking).
Provide pre-drilled chassis "jigs" for students with fine motor challenges to ensure successful alignment.
Assessment of Understanding: The "Coast Test": Students release their chassis (without the trap) down a ramp; it must travel 10 feet in a straight line.
Materials / Resources: Balsa wood, brass tubing/straws (bearings), steel axles, graphite lubricant, carpenters' squares.