| LEVERS
AND PULLEYS MODULE MATRIX |
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SYNOPSIS |
SCIENCE
CONTENT |
THINKING
PROCESSES |
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1. |
LEVERS
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Students
are introduced to levers as devices that help lift weight or
overcome resistance. Students investigate the fulcrum, effort,
and load of one kind of lever (class-1) and conduct experiments
with a spring scale to discover the relationships between the
parts of lever systems. They draw and graph their results. |
•
A lever is a simple machine that people use to gain an advantage,
such as making work easier.
• An advantage is a benefit obtained by using a lever
(or other simple machine).
• Effort is the force needed to move a load or overcome
a resistance.
• Fulcrum is the point where a lever arm pivots.
• Load is a mass lifted or a resistance overcome by a
lever. |
•
Measure the effort to lift a load when the load remains constant
and the effort changes position.
• Measure the effort to lift a load when the effort remains
stationary and the load moves.
• Organize observations on a record sheet.
• Discover the relationships between the parts of a lever. |
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2. |
MORE
LEVERAGE |
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Students
investigate and diagram class-1, class-2, and class-3 lever
systems. They investigate and diagram common tools to determine
how the tools apply levers. |
•
A class-1 lever has the fulcrum between the load and the effort.
• A class-2 lever has the load between the effort and
the fulcrum.
• A class-3 lever has the effort between the fulcrum and
the load.
• Conventions are operating procedures that help people
communicate more efficiently.
• Advantage is a gain in effort, distance, or change of
direction resulting from the use of a simple machine. |
•
Observe the behavior of different kinds of levers.
• Compare the effort to lift loads with different kinds
of levers.
• Diagram the relative positions and sizes of lever components
in different systems.
• Analyze tools in terms of their application as levers. |
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3. |
PULLEYS |
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Students
are introduced to a second simple machine and discover how to
set up single fixed and single movable pulleys to lift a load.
They use a scale to quantify effort with single pulleys. They
go on to set up and diagram multiple pulley systems. |
•
A single-pulley system can be set up in two ways, fixed or movable.
• A single-movable-pulley system provides a mechanical
advantage for its user.
• A single-fixed-pulley system provides no mechanical
advantage, but changes the direction of the effort.
• A two-pulley system can be made with one fixed and one
movable pulley.
• A two-pulley system in which the effort is applied upward
provides a greater advantage than one in which the effort is
applied downward. |
•
Observe and measure the effort to lift a load with single-fixed-
and single movable-pulley systems.
• Organize information on a data sheet.
• Diagram and compare the components of four kinds of
pulley systems. |
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4. |
PULLEYS
AT WORK |
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Students
systematically investigate four pulley systems. They record
data on each system. They graph and determine the relationship
between the number of ropes pulling on the load and the effort
needed to lift it. They determine the distance that the load
and effort travel when work is done. Students determine the
advantage (and disadvantage) of different pulley systems. |
•
The effort needed to lift a load with a pulley system can be
predicted.
• The amount of work put into a system is equal to the
work output of the system. |
•
Observe and measure the effort to lift a load with one- and
two-pulley systems.
• Organize information on a data sheet.
• Determine the advantage of pulley systems.
• Measure and compare the distance the effort and load
travels in different pulley systems. |
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