Student Handout: Durham Fair Tractor Pull Dynamics

Part 1: Engage (Anchoring Phenomenon)

At the Durham Fair tractor pull, incredibly powerful machines struggle to pull a sled that gets progressively heavier as it moves. Sometimes the tractors pop a wheelie, spin out, or completely stall.

  1. Why do some tractors lift their front wheels off the ground?
  2. What causes a tractor to spin its tires instead of moving forward?
  3. How can a driver optimize their tractor to pull the sled the farthest?

Part 2: Explore (Simulation Investigation)

Use the Durham Fair Tractor Pull simulation to investigate the dynamics of the pull.

  1. Baseline Trial: Run a trial with the default settings. Note the final distance and the outcome status.
  2. Variable Testing: Systematically adjust variables such as weight distribution (front vs. rear), tire friction coefficient, and engine force.
  3. Data Collection: Record the maximum distance achieved, peak acceleration, and the final status (e.g., Full Pull, Wheelie, Wheel Slip, Stall) for each configuration.
  4. Force Observation: Carefully observe the force vectors (Normal Force, Friction, Engine Force, Net Force) during the pull.

Part 3: Explain (Sensemaking)

Based on your data, explain the physics behind a successful “Full Pull”.

  1. Force Balance: How does changing the weight distribution affect the normal force and available traction on the rear wheels?
  2. Outcome Analysis: Under what conditions does a “Wheel Slip” occur? Under what conditions does a “Wheelie” occur?
  3. Evidence-Based Reasoning: Support your explanation with specific evidence from the simulation and Newton’s Second Law. How does the interplay of forces dictate the tractor’s acceleration?

Part 4: Elaborate/Evaluate (Argumentation & Modeling)

Develop a model or draft a scientific argument (CER format) that connects your observations to the broader principles of forces and motion.