1 the swinging pendulum 8 th grade science butler middle school lowell, ma bob, paul & ms adams...
TRANSCRIPT
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TheSwinging Pendulum
8th Grade ScienceButler Middle School
Lowell, MA
Bob, Paul & Ms AdamsApril 4, 2012
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Must See TV TonightCh 2, WGBH, 9pm
This may help you with MCAS
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Having Fun with a Pendulum
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AllPE
TopSpeed
KE
AllPE
Swinging Pendulum Assume: Negligible Friction and Air Resistance
Also assume string has negligible mass
bob
Unbalanced Force!Pivot Point
No UnbalancedForces
TopSpeed
KE
No UnbalancedForces
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The bob’s Energy All Potential at the high points.
All Kinetic at the low point. Is the kinetic energy equal, bigger, or smaller than potential energy at the high point?
In between the ‘bob’ has both potential & kinetic and they are continuously transforming into each other.
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The bob’s Motion Between the high points and the low point:
The bob is either speeding up or slowing down. This requires an unbalanced force.
The change in speed is called: __________
At the high points the bob’s speed is zero and a change of direction occurs.
At the low point the bob’s speed is maximum and there is no unbalanced force. What does Newton’s 1st Law say about this?
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VocabularyOne Swing of the bob is also called: One Round Trip One Back and Forth One Cycle One Vibration
Period: Time for One Swing of the bob
Frequency: Number of Swings per Second
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Measure Period by timing 10 swings, then divide by 10
Period = Total Time / 10
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Your Experiment
Determine how length of string and mass of the bob
affects period.Can you create a
pendulum with a period of 1 second?