Tailgating Lesson

Content Area: Physics (11-12)
Topic: Kinematics
Sub-Topic: Tailgating

Computer requirements: Vensim, STELLATM, or Excel
Prior content covered: Linear velocity and acceleration
Estimated time for computer portion of lesson: 30 - 60 min

Essential Questions or Ideas to address:

• What is a good rule for safe following distances?
• How do model assumptions affect model outcomes?

The lesson (90-min block): Students build or manipulate a pre-built Vensim or STELLATM model which is based on the braking distance model but now involves two cars. For a range of velocities, students try to find the minimum safe following distance for a particular set of braking conditions. Depending on time alloted, each student can be assigned one velocity and the whole class can explore only one acceleration. Or each student can explore the whole range of velocities for a particular acceleration.

After the data is collected, students compare their model results to the safe following rules learned in driver's education classes. Students can then discuss model assumptions and variables which can effect the results. For more details, see the Tailgating Activity Packet. Sample output assuming different following distances may be found at A Comparison of Tailgating Scenarios.

• For a given  acceleration, the relationship between initial velocity and braking distance is linear.

Evaluation of lesson effectiveness:  Like braking distance, this can represent  a powerful connection between classroom learning and the "real-world".  Students do struggle with the graph interpretation, but teachers could modify the model output to simplify the graphs.

Alternate presentation:  This activity was originally described as a spreadsheet activity in The Physics Teacher (R. C. Nicklin, "Kinematics of Tailgating", February 1997 , Volume 35, Issue 2, pp. 78-79) .

Math topics: Linear and quadratic equations, graph interpretation for those equations, using a graph to determine events, data collection and analysis

Extensions:  Students can investigate other variables in the model, such as reaction time and braking acceleration as they relate to driver awareness or road conditions.  Students could prepare safety posters or lessons based on their findings. Drunk Driving and Tailgating illustrates the impact of blood alcohol concentration on the driver's reaction time.

Standards:

MSDE (from the website as of 9/05):

 Physics/Core Learning Goals Science Indicator 5.1.2 The student will use algebraic and geometric concepts to describe an object's motion. Assessment Limits direction, position, distance/displacement, speed/velocity, motion with a constant acceleration, one and two dimensional motion, frames of reference Goal 5 Concepts Of Physics The student will demonstrate the ability to use scientific skills and processes (Core Learning Goal 1) to explain and predict the outcome of certain interactions which occur between matter and energy. Expectation 5.1 The student will know and apply the laws of mechanics to explain the behavior of the physical world.

The standards do not directly address kinematics, but an understanding of motion is necessary before students can address the standards as they appear here.

National Science Standards:

Physical Science: Motion and Forces:
Objects change their motion only when a net force is applied. Laws of motion are used to calculate precisely the effects of forces on the motion of objects. The magnitude of the change in motion can be calculated using the relationship F = ma, which is independent of the nature of the force.  Whenever one object exerts a force on another, a force equal in magnitude and opposite in direction is exerted on the first object.

AAAS Benchmarks:

The Physical Setting: Forces of Nature:

• The change in motion of an object is is proportional to the applied force and inversely proportional to the mass.
• All motion is relative to whatever frame of reference is chosen, for there is no motionless frame from which to judge all motion.

 Home | Contact | Site Map | Search