Transportation Chapter 1: Driving the Roads

Chapter Challenge
A newly licensed young driver asking to use the family car on a Friday night date establishes the scenario. Students are challenged to demonstrate to their parents that they know how to apply understanding of the laws of motion to safe driving. They can demonstrate this understanding with a convincing argument, a letter about an unsafe intersection, or a presentation about how distractions and alcohol affect response time that includes calculations of stopping distance.

Chapter Summary
To gain knowledge and understanding of physics principles necessary to meet this challenge, students work collaboratively on activities in which they apply concepts of kinematics as they collect and analyze data collected in investigations of speed, acceleration, velocity, and friction. These experiences engage students in the content identified in the National Science Education Standards.

Activity Summaries

Physics Principles

Activity One: Response Time

Using a response timer, students explore the time required for a driver to respond to a hazard. This activity introduces students to the process of beginning with their own ideas and predictions, then implementing an investigation that results in both qualitative and quantitative data.

• Series circuits
• Switches
• Response time

Activity Two: Speed and Following Distance

Strobe, or multiple exposure photos of a moving vehicle are used to discuss speed and acceleration. Students then use a sonic ranger to measure how fast they walk and obtain a computer generated graph of their speed. Information about speed is then connected to response time with a discussion of tailgating.

• Average speed
• Using data as basis for predictions
• Speed, distance, and time relationships

Activity Three: Stopping Your Car

Students use sloped tracks to investigate speed and distance a car travels before stopping. They then examine data on time and distance required to stop a vehicle moving at various speeds. This is connected to the total time required to respond to a hazard, apply force to the brake, and slow the motion of the vehicle to a complete stop.

• Acceleration
• Average speed
• Friction

Activity Four: Putting It All Together

Distractions that slow response time - talking, loud music, and alcohol - are the focus of this activity in which students plan and conduct a scientific investigation to answer a question they posed themselves about braking distance, safe following distance, and speed. A computer simulation allows students to test their ideas.

• Acceleration
• Instantaneous speed
• Average speed

Activity Five: Intersections With a Yellow Light

Using a spreadsheet model of an intersection, students explore how reaction time, speed, and stopping distance affect what they should do at a yellow light. This also introduces them to how transportation engineers use a computer simulation to model various factors affecting decisions about speed limits and traffic light cycles.

• Acceleration
• Instantaneous speed

Activity Six: Yellow Light Dilemma...

Students now have the opportunity to apply their understanding of response time, following distance, and braking distance to identify the stop, go, and dilemma zones at intersections when they see a yellow light.

• Acceleration
• Velocity and speed
• Inertia

Activity Seven: Driving on Curves

Students perceptions and prior "learning" about the force needed to change the direction of a moving object are challenged in this activity. After performing investigations, they reflect on the discrepancy between their perceptions and observed results. Students then read for more information on how forces change the direction of motion.

• Gravity
• Force
• Circular motion

Activity Eight: Banking the Turns

The concept that motion on a curve requires a centripetal force to keep the car "pushing" towards the curve is the focus of this activity. Predicting, observing, and describing the direction, relative speed, and the relationship of the radius and speed on a turntable enables students to develop and test their understanding of this concept about force.

• Gravity
• Circular motion
• Centripetal force

Activity Nine: Skids!

Students apply what they now know about speed, reaction time, stopping a car, and handling a car on a turn to investigate what to do in a skid. They analyze observable results in terms of laws of motion. This activity concludes with students reading about cars with front wheel and rear wheel drive and horizontal motion of the projected object, and predict its trajectory.

• Friction
• Inertia