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 * '''Cabinet:''' Mechanic (Will be permanently installed in lecture halls)
 * '''Bay:''' {B12}
 * '''Shelf:''' "1"		  * '''Cabinet:''' Mechanics (Will be permanently installed in lecture halls eventually)
 * '''Bay:''' (B12)
 * '''Shelf:''' #1
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Two small lead balls are supported on a cross-beam which is suspended by a fine wire(glass) to form a torsion pendulum. 2 Large lead spheres are placed opposite the small balls to exert a force onto the suspended system. Two small lead balls are attached to a cross-beam which is suspended by a fine wire to form a torsion pendulum. Two large lead spheres are placed opposite the small balls to exert a force onto the suspended system.
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   ||<:25%> '''Equipment:'''||<:25%> '''Location''' || ID Number||
   || || || ||
   ||Cavendish Balance||ME, B12, 1|| 1L10.30 ||
   ||Laser ||... || ...||		 ||<:style="width: 60%" :40%>'''Equipment'''||<:30%>'''Location'''||<:25%>'''ID Number'''||
|| || || ||
||Cavendish Balance||ME, Bay B12, Shelf #1|| 1L10.30 ||
||Laser ||... || ...||
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 1. Currently Setup requires a 48 hour notes before lecture. Once there installed within the room this condition maybe lifted.
 1. Make sure the Cavendish Torsion Balance is level on a bench or platform that has no vibration. 		 1. Setup requires 48 hour advanced notice before lecture. (Once the Cavendishes are installed in the room this condition may be lifted.)
 1. Level the Cavendish Torsion Balance on a vibrational free platform.
 1. The two large lead spheres are then placed opposite the smaller balls
 1. The system must then be allow to reach equilibrium, this takes a few hours.
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 1. The Large Masses are made of Lead and weight about 1.5Kg
 1. The Torsion Balance inside the Cavendish is very delicate and can break.		  1. The large masses are made of lead and weight about 1.5Kg
 1. The torsion balance inside the Cavendish is very delicate and must be handled carefully. Also carry by its base.
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'''Demonstration:'''
The two smaller masses have a mass of m=38g and are made of lead. They are suspended on a cross-beam torsion wire and have a distance of d=50.0mm for center-to-center of each ball. The two larger masses are made of lead too and have a mass of M=1.5Kg		 '''Demonstration:'''
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The objective of this experiment is to determine G. F = (GmM)(r^-2). The two large lead spheres are placed opposite the small balls, which will exert a torque and move cross-beam torsion wire system. The system is now allowed to come to a new equilibrium position which is shown by a laser beam reflected off the a small mirror that is attracted to the cross-beam torsion wire system. The reflected laser dot will be on the opposite wall and the motion of the cross-beam can be observed and measured. The objective of this experiment is to determine a numerical value for Newton's constant, G. F = (GmM)(r^-2). The two large lead spheres are then moved to the opposite position from the initial setup position. This exerts a torque which moves the cross-beam torsion wire system. Now let the system come to a new equilibrium position which is shown by a laser beam reflected off a small mirror that is attached to the cross-beam torsion wire system. The laser dot is reflected to the opposite wall and hence the motion of the cross-beam can be observed and measured. The finial equilibrium position will take several hours as the simple harmonic motion of the torsion pendulum damps out.
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Allowed the system to come to an equilibrium position.

The large lead balls are then shifted to the other smaller lead ball to give a torque in the opposite direction. The cross-beam torsion wire system is then aloud to find a new equilibrium as it damped out in a simple harmonic motion. Full damping requires over an hour and a half.
  * The two smaller masses have a mass: m=38g
 * The center-to center distance between of the smaller ball: d=50.0mm.
 * The two larger masses have a mass: M=1.5Kg
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 1. [attachment:CavendishManual.pdf Cavendish Manual]  1. [attachment:CavendishManual.pdf Cavendish Manual (pdf)]

Cavendish Balance, 1L10.30

Location:

  • Cabinet: Mechanics (Will be permanently installed in lecture halls eventually)

  • Bay: (B12)

  • Shelf: #1

attachment:CavendishBalance.jpg (photo from Pasco online)

Description:

Two small lead balls are attached to a cross-beam which is suspended by a fine wire to form a torsion pendulum. Two large lead spheres are placed opposite the small balls to exert a force onto the suspended system.

Equipment

Location

ID Number

Cavendish Balance

ME, Bay B12, Shelf #1

1L10.30

Laser

...

...

Setup:

  1. Setup requires 48 hour advanced notice before lecture. (Once the Cavendishes are installed in the room this condition may be lifted.)
  2. Level the Cavendish Torsion Balance on a vibrational free platform.
  3. The two large lead spheres are then placed opposite the smaller balls
  4. The system must then be allow to reach equilibrium, this takes a few hours.

Cautions, Warnings, or Safety Concerns:

  1. The large masses are made of lead and weight about 1.5Kg
  2. The torsion balance inside the Cavendish is very delicate and must be handled carefully. Also carry by its base.

Demonstration:

The objective of this experiment is to determine a numerical value for Newton's constant, G. F = (GmM)(r^-2). The two large lead spheres are then moved to the opposite position from the initial setup position. This exerts a torque which moves the cross-beam torsion wire system. Now let the system come to a new equilibrium position which is shown by a laser beam reflected off a small mirror that is attached to the cross-beam torsion wire system. The laser dot is reflected to the opposite wall and hence the motion of the cross-beam can be observed and measured. The finial equilibrium position will take several hours as the simple harmonic motion of the torsion pendulum damps out.

  • The two smaller masses have a mass: m=38g
  • The center-to center distance between of the smaller ball: d=50.0mm.
  • The two larger masses have a mass: M=1.5Kg

attachment other photos

attachment other photos

attachment other photos

attachment other photos

References:

  1. [http://store.pasco.com/pascostore/showdetl.cfm?&DID=9&Product_ID=1655&groupID=306&Detail=1 Pasco]

  2. [attachment:CavendishManual.pdf Cavendish Manual (pdf)]

[:Demonstrations:Demonstrations]

[:Instructional:Home]

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