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Content Area: Physics (11-12)
Topic: Kinematics
Sub-Topic: Free Fall
Computer requirements: Vensim, STELLATM, Interactive
Physics or Excel
Prior content covered: Linear velocity and
acceleration
Estimated time for computer portion of lesson:
45 min
Essential Questions or Ideas to address:
- What does free fall look like in various worlds?
- How does free fall affect the motion of objects that are
thrown upward or downward compared to those that are just dropped?
The lesson (90-min block): After
investigating free fall in the laboratory, students can build or use a
Vensim/STELLA model, Excel spreadsheet or an Interactive Physics simulation to
further investigate free fall. In one activity, they use the
model to compare free fall on earth, the moon, and another planet. In a
second activity, they compare the motion of three objects on earth: one
is dropped, one is thrown downward and one is thrown upward. For
an example of a model and companion activities see the Free Fall Activity Packet.
Common misconceptions addressed:
- When an object is thrown upward, at the top of the flight
path, the acceleration is zero.
- Objects thrown upward and downward retain some "extra"
acceleration that is observable in the velocity-time graph.
Evaluation of lesson effectiveness: Students
find the first activity interesting for its novelty. This is
easier to do in STELLA or Excel where comparative graphs can be
maintained while the acceleration is changed. The second activity can
be accomplished in any of the modeling environments. The position-time
and velocity-time graphs for these three motions
provide rich opportunities to assess student understanding of graphs of
these variables and the meaning of slope and y-intercept, especially on
the velocity - time graph.
Alternate presentation: There are many
applets available on the web.
Math topics: Linear and quadratic equations,
graph interpretation for those equations
Extensions: The falling filters and
parachute models presented under the sub-topic of drag are natural
extensions of this model.
Standards:
MSDE (from the website as of 9/05):
| Physics/Core Learning Goals |
| Science Indicator 5.1.2 |
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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
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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.
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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.
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