Labs for Forces in Two Dimensions

Lesson Plans || Learning Outcomes and Activities || Teacher Notes || Labs
 

 

We have a collection of ~150 labs in the Laboratory section of the website. Each lab was intended to be used with a lab notebook where students report their data and findings and state their conclusion with supporting evidence and reasoning. The intent was to provide a relatively clear purpose (or question) to students that they would need to address AND to limit the amount of directions. The hope is that the purposes and students' ability to design a procedure would drive the lab activity (in contrast to a detailed set of step-by-step procedures being the driving force of students' activity). As such, each of our labs comes with a Question and Purpose and a short paragraph describing what should be included in students' lab report. On occassion, students are also provided a graphic organizer, data table, or other item to be taped into their notebook. The following pages may be useful for those teachers who wish to adopt or simply trial our Labs with a Purpose approach:

Our Thoughts on the Approach || About Lab Notebooks || Teacher Guides for All Labs

 

Lab 1: Getting Hung up by Tension

Question:
What is the result of conducting a force analysis on an object at equilibrium?

Purpose:
To conduct three different equilibrium analyses in order to determine the net force upon three different objects.

A complete lab write-up includes a Title, a Purpose, a Data section, and a Conclusion/Discussion of Results. The Data section should include a diagram of the three situations being analyzed with the magnitude and direction of all forces clearly stated on the diagram; a labeling convention (e.g., A= , B= , C= , etc.) should be used to distinguish between the forces. Calculations and analysis should be clearly shown. A net force should be determined. The Conclusion/Discussion should identify the calculated net force for the three situations and should include an error analysis for each situation.

 

Lab 2: Sign Hanging Lab

Question:
How does the measured tension in the string supporting a sign compare to the theoretically predicted value?

Purpose:
To compare the measured tension in the string supporting a sign to the tension which would be theoretically predicted based on the mass of the sign and the angle the two strings make with the horizontal.

A complete lab write-up includes a Title, a Purpose, a Data section, and a Conclusion/Discussion of Results. The Data section should include a diagram of the sign and supporting strings; strategic measurements should be recorded on the diagram. Calculations of the theoretically predicted tension should be clearly shown in an organized fashion beginning with a force triangle . The Conclusion/Discussion should answer the question posed in the Purpose and include an error analysis with a percent difference calculation.

 

 

Lab 3: Inclined Plane Lab

Question:
How is the weight of an object mathematically related to the component of the weight directed parallel to the inclined plane?

Purpose:
To determine the mathematical equation which relates the weight of an object to the component of the weight which is directed parallel to an inclined plane.

A complete lab write-up includes a Title, a Purpose, a Data section, a Conclusion, and a Discussion of Results. The Data section should include a diagram of the inclined plane to which you were assigned, with measurements included on the diagram. Class data for the various incline angles should be recorded. Some form of analysis leading up to an equation should be documented in the Data section. The Conclusion should state the mathematical relationship in both words and an equation. The Discussion of Results should thoroughly explain the logical connection between the collected data and the conclusion.

 

 

Lab 4: On a Roll Challenge Lab

Question:
What is the speed of a cart after rolling from rest a given distance along an inclined plane with a specified angle? How does it relate to the predicted speed?

Purpose:
To use Newton's laws, vectors and motion equations to predict the speed of a cart near the bottom of a hill and to evaluate the accuracy of the prediction with a measurement.

A complete lab write-up includes a Title, a Purpose, a Data section, a Conclusion and a Discussion of Results. The Data section should include a diagram of the inclined plane with assigned values of mass and distance and the appropriate x-y measurements needed to determine the incline angle. A free-body diagram and NewtonÕs law analysis is included in an effort to determine the predicted speed. All work is clear, labeled and documented. A photogate time and flag width should be included along with a calculation of the measured speed. The Conclusion reports the predicted and the measured speed. The Discussion of Results should include an error analysis along with a percent error calculation.

 

Lab 5: Modified Atwoods Machine

Question:
What
is
the
mathematical
equation
relating
the
final
velocity
(after
accelerating
1.00
m
from
rest)
of
a
 low‐friction
cart
(or
air
track
glider)
to
the
amount
of
hanging
mass
on
a
modified
Atwood’s
machine?
 


Purpose:
To
experimentally
derive
an
equation
relating
the
final
velocity
(after
accelerating
1.00
m
from
rest)
 of
a
low‐friction
cart
(or
air
track
glider)
to
the
amount
of
hanging
mass
for
a
modified
Atwood's
 machine.



A
complete
lab
write‐up
includes
a
Title,
a
Purpose,
a
Data
section,
a
Conclusion
and
a
Discussion
of
 Results.

Data
section
should
include
a
data
table
with
several
trials
for
varying
mass
(hanging)
and
 the
corresponding
values
for
the
final
velocity.

The
results
of
a
power
or
linear
regression
analysis
 should
be
conducted
and
statistical
information
reported.
The
development
of
the
equation
should
be
 well‐documented.
The
Conclusion
should
(as
always)
respond
to
the
question
raised
in
the
Purpose.

 The
Discussion
of
Results
should
include
an
error
analysis.
As
part
of
the
analysis,
theoretical
 considerations
(free‐body
diagram,
Newton’s
laws
analysis,
kinematics)
which
could
provide
a
 prediction
of
the
mathematical
equation
should
be
discussed.

The
equation
reported
in
the
 Conclusion
section
should
be
compared
to
a
theoretically‐derived
equation.


 

 

 

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