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Deletions are marked like this. Additions are marked like this.
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  Newton's First Law, [:Newtons1STLaw#InertiaofRest: 1F20. Inertia of Rest]   Linear Momentum, [:Linear_Momentum#Collisions1D: 1N30. Collisions in One Dimension]
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 * '''Cabinet:''' [:MechanicsCabinet:Mechanic (ME)]
 * '''Bay:''' [:MechanicsCabinetBayA1:(A1)]
 * '''Shelf:''' #1,2,3.. 		 * Floor Item: [:MechanicsCabinet#MEFloorItems: ME, South Wall]
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 attachment: mainPhoto attachment:ElasticActionShot04-400.jpg
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Insert succinct description of demonstration. Unequal mass air gliders collide. For example, a small cart hits a big one elastically. The big one is placed so that after the collision both carts hit the ends simultaneously. The carts will again collide at the original place.
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||apparatus||ME, Bay B1, Shelf #2|| ||
||all other parts||ME, Bay B1, Shelf #2|| ||
||...||ME, Bay B1, Shelf #2|| ||		 ||2.5m Air Track||[:MechanicsCabinet#MEFloorItems: Floor Item: ME, South Wall]|| ||
||Air Track Carts||[:MechanicsCabinetBayA4: ME, Bay A4, Shelf #3]|| ||
||[:RedWhiteGasCart:Red & White Gas Carts]||In Lecture Halls 2103, 2223, 2241|| ||
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 * ''''' '''''
  * '''''This demonstration requires a supply of compressed air.'''''
 * '''''To accommodate the 2.5 meter track, this demonstration requires two lecture benches.'''''
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 1. List steps for setup then procedure.
 1. ...		  1. Place air track on lecture bench, and connect the compressed air supply from the lower white panel of the [:RedWhiteGasCart:Red & White Gas Cart] to the track using an air hose.
 1. Place two gliders on the track, one on an end of the track and the other roughly in the middle.
 1. Make sure that the gliders have their respective spring-equipped sides facing each other.
 1. Turn on the air supply by opening the valve located on the lower white panel of the cart.
 1. If the gliders seem to slide in one direction, this is most likely due to the track being unlevel. Adjust the set screws until this no longer occurs. It is a good idea to do this ahead of time.
 1. Give the glider on the end a good push toward the glider at rest to create a collision.
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 *  * Make sure you are using compressed air and NOT methane gas which is extremely flammable!
 * Running the compressed air line is noisy!!
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Discuss the physics behind the demonstration, explaining some of the various steps of the demonstration when appropriate. In conservative systems, momentum is always conserved. In the lab frame, one glider is in motion and one is at rest. Thus, the total momentum of the system is P,,0,, = m,,1,, * v,,1,, where m,,1,, is the mass of the glider in motion and v,,1,, is its speed. In an perfectly elastic collision, there is no loss of kinetic energy. Invoking conservation of kinetic energy and momentum then, the velocities of each glider after the collision can be determined in terms of their respective masses and the speed of the first glider. The result is this:
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||attachment: photo||attachment: photo||attachment: photo||attachment: photo|| v,,1,,' = (m,,1,, - m,,2,,) * v,,1,, / (m,,1,, + m,,2,,)
              
v,,2,,' = 2 * m,,1,, * v,,1,, / (m,,1,, + m,,2,,)

From this result, it is easy to predict the outcome of a collision. The second glider will always obtain a velocity in the same direction as the first glider was moving. Its speed depends on the masses of both gliders and the initial speed of the first one. If the first glider is more massive than the second one, both gliders will move in the same direction. If the first glider is less massive than the second one, it will bounce back in the opposite direction from which it came. In either of those two cases, the first glider will always move at a slower speed than it was initially.

||attachment:AirHose01-250.jpg||attachment:AirHose02-250.jpg||attachment:AirHose03-250.jpg||
||attachment:ElasticGliders-01-250.jpg||attachment:ElasticLargerGliders-03-250.jpg||attachment:ElasticShortGliders-04-250.jpg||
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 * List any references  * [http://hyperphysics.phy-astr.gsu.edu/hbase/elacol.html Elastic & Inelastic Collisions - Hyperphysics]
 * [https://en.wikipedia.org/wiki/Elastic_collision Elastic Collisions - Wikipedia]

[:PiraScheme#Mechanics: Table of Mechanics Demonstration]

[:MEEquipmentList: List of Mechanics Equipment & Supplies]

[:Demonstrations:Lecture Demonstrations]

Air Track Collisions of Unequal Masses, 1N30.34

Topic and Concept:

  • Linear Momentum, [:Linear_Momentum#Collisions1D: 1N30. Collisions in One Dimension]

Location:

attachment:ElasticActionShot04-400.jpg

Abstract:

Unequal mass air gliders collide. For example, a small cart hits a big one elastically. The big one is placed so that after the collision both carts hit the ends simultaneously. The carts will again collide at the original place.

Equipment

Location

ID Number

2.5m Air Track

[:MechanicsCabinet#MEFloorItems: Floor Item: ME, South Wall]

Air Track Carts

[:MechanicsCabinetBayA4: ME, Bay A4, Shelf #3]

[:RedWhiteGasCart:Red & White Gas Carts]

In Lecture Halls 2103, 2223, 2241

Important Setup Notes:

  • This demonstration requires a supply of compressed air.

  • To accommodate the 2.5 meter track, this demonstration requires two lecture benches.

Setup and Procedure:

  1. Place air track on lecture bench, and connect the compressed air supply from the lower white panel of the [:RedWhiteGasCart:Red & White Gas Cart] to the track using an air hose.

  2. Place two gliders on the track, one on an end of the track and the other roughly in the middle.
  3. Make sure that the gliders have their respective spring-equipped sides facing each other.
  4. Turn on the air supply by opening the valve located on the lower white panel of the cart.
  5. If the gliders seem to slide in one direction, this is most likely due to the track being unlevel. Adjust the set screws until this no longer occurs. It is a good idea to do this ahead of time.
  6. Give the glider on the end a good push toward the glider at rest to create a collision.

Cautions, Warnings, or Safety Concerns:

  • Make sure you are using compressed air and NOT methane gas which is extremely flammable!
  • Running the compressed air line is noisy!!

Discussion:

In conservative systems, momentum is always conserved. In the lab frame, one glider is in motion and one is at rest. Thus, the total momentum of the system is P0 = m1 * v1 where m1 is the mass of the glider in motion and v1 is its speed. In an perfectly elastic collision, there is no loss of kinetic energy. Invoking conservation of kinetic energy and momentum then, the velocities of each glider after the collision can be determined in terms of their respective masses and the speed of the first glider. The result is this:

v1' = (m1 - m2) * v1 / (m1 + m2)

v2' = 2 * m1 * v1 / (m1 + m2)

From this result, it is easy to predict the outcome of a collision. The second glider will always obtain a velocity in the same direction as the first glider was moving. Its speed depends on the masses of both gliders and the initial speed of the first one. If the first glider is more massive than the second one, both gliders will move in the same direction. If the first glider is less massive than the second one, it will bounce back in the opposite direction from which it came. In either of those two cases, the first glider will always move at a slower speed than it was initially.

attachment:AirHose01-250.jpg

attachment:AirHose02-250.jpg

attachment:AirHose03-250.jpg

attachment:ElasticGliders-01-250.jpg

attachment:ElasticLargerGliders-03-250.jpg

attachment:ElasticShortGliders-04-250.jpg

Videos:

References:

[:Instructional:Home]

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