Balls and Plate , 4A30.22

Location:

• Cabinet: Thermodynamics Cabinet

• Bay: (A3)

• Shelf: #1

attachment:4A30-22_01.jpg

Description:

Insert description of apparatus, its component, what it is demonstrating.

Setup:

1. Make sure you have the balls with two sizes, one is over and one is under the hole size, the brass plate with hole in the middle, and the stand.
2. Install the burner with the gas source.
3. Have the liquid nitrogen in the holder.

Cautions, Warnings, or Safety Concerns:

1. Beware of the heated plate.

Demonstration:

When the plate is heated, it expands the hole in the middle of the plate. [The molecular bonds are lengthened, when the material expands. Try to think in this way, a group of people standing in a tight circle with elbows linked. Then they lengthen their "bonds" by moving to hold hands at arms length. They also have to expand the circle by standing back, while they all stand further apart. This is like the molecular bonds around the hole.] So the ball can get through it. You have two options to show student by following.

Option A. Shrink or extended ball

1. Demonstrate to students that the smaller ball can get through the hole and the larger ball cannot.
2. Heat the smaller ball or put the larger ball in the liquid nitrogen, this will make the opposite situation from the previous.

Option B. Extended Hole

1. Demonstrate to students that the smaller ball can get through the hole and the larger ball cannot.
2. Heat the ball by the burner until you sure that the hole get larger than before.
3. Demonstrate to students again, this time both balls should get through the hole.

References:

1. [http://wiki.answers.com/Q/When_a_block_with_a_hole_in_it_is_warmed_why_doesn%27t_the_material_around_the_hole_expand_into_the_hole_and_make_it_smaller Wikianswers]

[:ThermalProperties:Thermal Properties of Matter]

[:Demonstrations:Demonstrations]

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