tesla simple machines 2010 pulleys. the big idea of this investigation a simple machine is a...
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TESLA Simple Machines 2010
Pulleys
The Big Idea of this Investigation
A simple machine is a mechanical device that makes work easier by magnifying, modifying, transferring, or changing the direction of applied force. Simple machines are the elementary "building blocks" of which all complicated machines are made.
Knowledge We Will Build on From Prior Investigations
Work = Distance X Force
Force is a push or pull applied to an object.
Friction is the number one enemy of simple machines. It increases the amount of force needed to do work.
Wheels reduce the amount of friction between an object and the surface over which it moves.
A wheel and axle can work together to magnify force and make work easier.
ENGAGING SCENARIO
In our previous investigations we have discovered how simple machines can make work easier by modifying or magnifying the force applied to objects in order to complete a task. A pulley is another simple machine that we have not investigated that could help us raise objects to higher locations. In this investigation we need to find out if using a pulley to lift an object requires less force than just lifting the object by itself.
• What is the problem we need to solve? • What do we need to investigate?
Discuss ideas with a partner for a possible focus question. Your focus question should be connected to what the scenario wants us to do…
Focus Question (What is the problem?)Focus Question (What is the problem?)
How can we determine if using a pulley to lift an object requires less force than just lifting the object by itself?
Prediction (related to the focus question) Prediction (related to the focus question)
Prediction:I predict that _______________ because____________If _____________________Then___________________
Prediction:I predict that _______________ because____________If _____________________Then___________________
Previous Knowledge Previous Knowledge
Share experiences with pulleys related to lifting objects.Share experiences with pulleys related to lifting objects.
NOTEBOOK ENTRY
Class Predictions (related to the focus question) Class Predictions (related to the focus question)
New VocabularyNew Vocabulary
Pulley• A wheel that rotates freely around an axle. The outer rim of
most pulleys is grooved to move on a rope or chain.
How does the fixed pulley and the moveable pulley change the direction of force applied in each of the models above?
Fixed Pulley: A pulley is attached to one location and does not move. It is used to move a load up, down, or sideways.
Moveable Pulley:A pulley that moves with the load along a rope or chain .
Preparing the InvestigationPreparing the Investigation
What are we going to change
What are we going to keep the same
NOTEBOOK ENTRY
Each group will be given a pulley, spring scale, string, fishing line, meter stick and a book to build your pulley system.
The way we lift the object
No PulleyFixed Pulley Moveable Pulley
• The distance we lift the object
• The object we lift
• The Spring Scale
Collecting DataCollecting Data
No Pulley
Trial # Height (cm)
Force Work
1
2
3
Average
Fixed Pulley
Trial # Height (cm)
Force Work
1
2
3
Average
Do you think the amount of force required to life the object will be the same with the fixed and moveable pulley?
Moveable Pulley
Trial # Height (cm)
Force Work
1
2
3
Average NOTEBOOK ENTRY
Making Meaning ConferenceMaking Meaning Conference
What is a mechanical advantage for using the fixed pulley?
In which direction was force applied to lift the book:• without the pulley?• with the fixed pulley?• with the moveable pulley?
How would you compare the amount of force and work required to lift the book with these 3 methods?
What is a mechanical advantage for using the moveable pulley?
Would using a pulley to lift an object have other mechanical advantages not related to force and work?
Claims and EvidenceClaims and Evidence
I claim that… I claim this because…
How can we determine if using a pulley to lift an object requires less force than just lifting the object by itself?
NOTEBOOK ENTRY
Reflection/ConclusionReflection/Conclusion
Revisit your original prediction… Explain how the evidence did or did not support your original prediction?
My prediction was accurate because…..I wish to revise my prediction because…
What did you learn…
What really surprised you…
What new questions do you have…
What would you like to know more about…
NOTEBOOK ENTRY