### Expanding Ball & Ring - Thermal Expansion (Joy Burton)

Joy Burton, Teacher @ Sutter Middle School

## Principles

1. An object can be said to be hot or cold only as compared to another object.

2. Thermal Expansion: Most substances expand when heated.

3. Laws of Thermodynamics

## Standards

7.7 Scientific progress is made by asking meaningful questions and conducting careful investigations. Students should develop their own questions and perform investigations. Students will:

• 7a  Select and use appropriate tools and technology (including calculators, computers, balances.....to perform tests, collect data, and display data.
• 7b  Use a variety of print and electronic resources (including the World Wide Web) to collect information and evidence as part of a research project.
• 7c  Communicate the logical connection among hypotheses, science concepts, tests conducted, data collected, and conclusions drawn from the scientific evidence.
• 7d  Construct scale models, maps, and appropriately labeled diagrams to communicate scientific knowledge.
• 7e  Communicate the steps and results from an investigation in written and oral presentations.
6.3 Heat moves in a predictable flow from warmer objects to cooler objects until all the o

bjects are at the same temperature. As a basis for understanding this concept students know:
• a. energy can be carried from one place to another by heat flow or by waves, including water, light and sound waves, or by moving objects.
• b. that when fuel is consumed, most of the energy released becomes heat energy.
• c. heat flows in solids by conduction (which involves no flow of matter) and in fluids by conduction and by convection (which involves flow of matter).
• d. heat energy is also transferred between objects by radiation (radia­tion can travel through space).

3. Heat and Thermodynamics. Energy cannot be created nor destroyed, although in many processes energy  is transferred to the environment as heat.  As a basis for understanding this concept students know:

• 3a. Heat flow and work are two forms of energy transfer between systems.
• 3b. The work done by a heat engine that is working in a cycle is the difference between the heat flow into the engine at high temperature and the heat (First Law of Thermodynamics) and that this is an example of the Law of Conservation of Energy.
• 3c. The internal energy of an object includes the energy of random motion of the object's atoms and molecules, often referred to as thermal energy. The greater the temperature of the object, the greater the energy of motion of the atoms and molecules that make up the object.
• 3d. Most processes tend to decrease the order of a system over time and that energy levels are eventually distributed uniformly.
• 3e. Entropy is a quantity that measures the order or disorder of a system and that this quantity is larger for a more disordered system.
• 3f. The statement "Entropy tends to increase" is a law of statistical probability that governs all closed systems (Second Law of Thermodynamics).
• 3g. How to solve problems involving heat flow, work, and efficiency in a heat engine and know that all real engines lose some heat to their surroundings.

## Materials needed

Ball and Ring Apparatus

Bunsen Burner Flame

Striker

Cold Water

## Procedure

2. Put the ball through the ring and remove.

4. Heat the ball for one minute in the bunsen burner flame.

5. Put the ball through the ring.

7. Heat the ring for one minute.

8. Put the ball through ring.

10. Cool the ring in the water.

11. Put the ball through the ring.

13.Cool the ball in the water.

14. Put the ball through the ring.

## Explanation

Most things expand when heated.

## Questions

1. What does heat do to matter?
2. What does cooling do to matter?
3. Since heat is molecular energy, why does expansion happen? Explain in terms of molecular motion.
4. Does heating cause an increase in weight?
Everyday examples of the principles illustrated
• Aircrafts expand/contract: Use of rollers to isolate cabin from the body.
• Thermal expansion of plutonium
• Railways
• Bridges: Use of rollers to create a space between the bridge spans while other end is chastened securely to the bridge span.
• Buildings, Houses: , Earthquake "proof", Pipes
• Loose phone lines
• Heat tops of jars to loosen the cap.
• Thermostats in heating systems, home appliances (electric iron, the toaster, refrigerator) expand with an increase in temperature and contracts when there is a decrease in temperature.

## References

California State Science Standards

Thermal Expansion