Large Ball and Ring Stand, 4A30.20
Topic and Concept:
Thermal Properties of Matter, 4A30. Solid Expansion
pira200 Listed
Location:
Cabinet: Thermodynamics Cabinet
Bay: (A3)?
Shelf: #1?
Description:
This demonstration has a ball and ring with stand. It demonstrates the thermal expansion of the material by heating the ball.
Equipment |
Location |
ID Number |
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A ring with stand and a ball with hanger |
4A30.20 |
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Burner with an iron ring tripod and wire net screen |
location |
NA |
An iron ring tripod and a screen |
location |
NA |
Safety grove and glasses |
location |
NA |
Rooms 2103, 2241, (and 2223 upon request) |
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Important Setup Notes:
This demonstration requires a supply of methane gas usually provided by the red and white gas carts found in rooms 2103, 2241, (and 2223 upon request).
Setup and Procedure:
To light the burner, connect the attached gas hose to the gas out (red panel) on the red and white gas cart.
- Open the gas valve.
- Light a match and bring it near the top of the burner.
- The flame will ignite the gas. Adjust the flame height accordingly by adjusting the valve.
- Show that the ball can get through the ring.
- Put the lit burner beneath the tall ring stand with the screen on the top.
- Lower the ball onto the screen using the attached hook. It will take about a minute for the ball to heat up enough to not fit through the ring
- Take the ball off the stand and try to lower the ball through the ring.
If the ball fits through the ring, repeat steps 7 & 8. Otherwise, let the ball rest on the ring. As it cools, it will eventually shrink enough to drop through the ring.
Cautions, Warnings, or Safety Concerns:
- Always use the gloves and safety glasses throughout this demonstration.
- Beware of the heated plate - contact with skin could cause severe burns!
Discussion:
When the ball is heated, its dimensions increase while maintaining their relative proportions. Heating causes the molecular bonds to lengthen, which causes the material to expand. This is considered a 2D expansion since the quantity of importance for the ball to fit through the ring is the cross sectional area. The expansion can be described by ΔA/A = αA*ΔT = αL2*ΔT where A is the area at temperature Ti, ΔA is the change in area when the material is at temperature Tf, ΔT is Tf - Ti, and α is the coefficient of thermal expansion which depends on the material. See references below for more information.
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Videos:
References: