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Lesson on Modeling of Motion


Objective: To model the motion of an object subject to a constant force.

Principle: Newton's second law of motion.

Prerequisite: The students should have clear understanding of of force, motion, velocityacceleration, and simple machines.

Experiment: Modified Atwood's machine









Model Development

Modeling begins with the description of related terms such as frame of reference, one-dimensional motion, and acceleration. Measurable parameters that might be expected to exhibit some cause-effect relationship should be identified. A variable under direct control by the experimenters is identified as the independent variable, while the effect is identified as the dependent variable.

The second phase of modeling is the formulation: to develop a functional relationship between the specified variables.

The third phase is the experimental design and data acquisition.

The final result of modeling development is a mathematical model together with evidence for a claim that accurately represents the behavior of the physical system, in this case the Atwood's Machine. The equation F = a. m should accurately describe the acceleration (a) when the force (F) and the mass (m) are varied independently. This equation represents a general law of nature. The experiment may validate specific models which conform to the law, as in this case.


Model Deployment

The developed model may be deployed to a variety of new physical situations in different ways. This helps free the students' realization of the model from the specific context in which it was developed. The model may be deployed to describe, to explain, to predict or to design a new situation. The above activity may involve the laboratory, however, the modeling process is more like traditional problem solving.


Example: The Atwood Machine