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,
velocity,
acceleration,
and simple
machines.
Experiment: Modified Atwood's
machine
Model
Development
Modeling begins with the
description of related terms such as frame of
reference, onedimensional motion, and acceleration.
Measurable parameters that might be expected to exhibit
some causeeffect 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
