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OSCILLATIONS

3A10.10 SIMPLE PENDULUM
3A15.10 PHYSICAL PENDULUM (ROD) 
3A15.25 PHYSICAL PENDULUM (RING)
3A20.10 MASS ON SPRING
3A60.10 TACOMA NARROWS BRIDGE COLLAPSE TAPE
3A60.40 DRIVEN MECHANICAL RESONANCE
3A70.10 WILBERFORCE PENDULUM
3A70.20 COUPLED PENDULA



3A10.10 Simple Pendulum

Suspend a simple pendulum from a rod. Use as visual aid when talking about pendulum. You can also determine period and show related to length.

!3a10_10.jpg

Setup Requirements: Assembled as needed. Stopwatch and meter stick optional. Several types of balls, weights and string available.

 

Equations: Period proportional to square root of length.

 

Safety Issues: None



3A15.10 Physical Pendulum (Rods)

Distributed mass pendulum instead of mass concentrated on end.

!3a15_10.jpg

Setup Requirements: Some assembly required. Meter stick, ring and baseball bat versions also available. 

 

Equations: Period depends on moment of inertia about pivot point. Period = 2 pi x square root of I/mgh.

 

Safety Issues: None


3A15.25 Physical Pendulum (Ring)

A ring oscillates on a rod. A v shaped piece of metal is placed over top of the rod to serve as a knife edge. Ring has the same period as simple pendulum with length equal to diameter of ring if thickness of ring is ignored.

 img_0107ring.jpg

Setup Requirements: Assembled as needed. Large ring period is 1.09 sec.

Equations:  Period ~ 2 x pi x (D/g)1/2

Safety Issues:  None



3A20.10 Mass on a spring

A mass oscillates slowly on a large spring. Use as visual aid or time to show period depends on mass.

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Setup Requirements: Assembled as needed. Stopwatch optional .

 

Equations: Period proportional to squareroot of m/k.

 

Safety Issues: None



3A60.10 Tacoma Narrows Bridge Film

Show a film of the oscillations of the bridge due to "resonance" and the subsequent collapse. Located in Miller Collection Tapes(yellow cover) Unit II. 

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Setup Requirements: Requires television & VCR on cart or VCR in classroom.

 

Equations: For information about physics involved see  http://www.umsl.edu/%7efeldmanb/pdfs/tacoma_bridge.pdf and  http://www.aapt.org/Store/upload/tacoma_narrows2.pdf

 

Safety Issues: None



3A60.40 Driven Mechanical Resonance

Signal generator connected to spring can be varied in frequency to show resonance in driven system. The signal generator could represent an earthquake and the spring a building.

 img_0055vib.jpg

Setup Requirements: Assembled as needed

 

Equations: If driving frequency(w) is near resonant frequency, amplitude builds up. Maximum amplitude = F(0)/(bw) where b is damping coefficient.

 

Safety Issues: Vibration amplitude so high spring comes loose.



3A70.10 Wilberforce Pendulum

Exhibits pendulum type motion, spring type motion, and rotational motion. Energy is passed back and forth between translational and rotational motion.

!3a70_10.jpg

Setup Requirements: Assembled as needed

 

Equations: Conservation of Mechanical Energy 

 

Safety Issues: None



3A70.20 Coupled Pendula

Hang multiple pendula from a rod. Start one moving. Another pendulum with same length will start moving. A pendulum with say twice the length will not move much.

!3a70_20.jpg

Setup Requirements: Assembled as needed. May differ from photograph.

 

Equations: None

 

Safety Issues: None



Last Updated: 07/12/2016