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Flowing Heat. 4 th grade science experiment. Matt Weisenberger, [email protected] University of Kentucky, Center for Applied Energy Research 2540 Research Park Dr., Lexington, KY 40511 859-257-0322. Overview. What is Heat? Three Experiments (1) Thermal Diffusivity

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Flowing Heat

4th grade science experiment

Matt Weisenberger, [email protected]

University of Kentucky,

Center for Applied Energy Research

2540 Research Park Dr., Lexington, KY 40511

859-257-0322


Overview
Overview

  • What is Heat?

  • Three Experiments

    • (1) Thermal Diffusivity

    • (2) Thermal Expansion

    • (3) Heat Capacity

  • Procedure

  •  Questions  Materials & Observations

  •  Results & Conclusions


What are heat temperature
What are Heat & Temperature?

  • Heat is ENERGY

  • The more heat-energy within a material, the hotter it will feel.

  • Heat always flows… from hotter areas to cooler areas… not the reverse.

  • Temperature is a measurement of the amount of heat within a material.

  • Materials that feel hot have a lot of heat in them. You feel that heat flowing into your cool hand.


Experiment 1 thermal diffusivity
Experiment 1: Thermal Diffusivity

  • What is thermal diffusivity?

  • Through which materials does heat flow faster?

    Answer

    Thermal diffusivity tells us how fast heat is conducted through a material. Materials such as copper and steel conduct heat faster than materials such as wood and plastic.


Experiment 1 materials
Experiment 1: Materials

  • Hot plate

  • Rods of copper, glass, and graphite (about 2 in. long X 3/8 in. diameter)

  • Paraffin wax


Procedure
Procedure

  • Stand three rods, made of different materials, with the exact same length (approx. 2 in. long) on a hot plate.

  • Turn the hot plate on “high.”

  • Place a small sliver of wax on the top surface of the rods and watch to see which rod melts the wax the fastest and which one the slowest.

  • The material upon which the wax melts first has the highest thermal diffusivity.

  • The material upon which the wax melts second has the second highest thermal diffusivity, etc.


Observations
Observations

Copper

wax melts 2nd

Glass

wax melts 3rd

Graphite

wax melts 1st


Results conclusions
Results & Conclusions

  • Graphite had the highest thermal diffusivity.

  • Copper had the 2nd highest thermal diffusivity.

  • Glass had the lowest thermal diffusivity.


Experiment 2 thermal expansion
Experiment 2.Thermal Expansion

  • What is thermal expansion?

  • Which materials expand more?

  • Answers

    Heat-energy causes the atoms of a material to vibrate. As they vibrate, they push each other apart. This causes the material to expand.


  • Experiment 2 materials
    Experiment 2: Materials

    • Metal Tubing:

      - copper: 8 ft long, about ¼ inch diameter, bendable

      - aluminum: 8 ft long, about ¼ inch diameter

    • Toothpicks (2)

    • Colored tape

    • Funnel

    • Rubber hose with hose clamps (6 in. long with a diameter that will fit snugly around tubing)

    • Laboratory ring stand with clamp

    • Wood blocks (about 2 in X 2 in X 2 in)

    • Source of hot water

    • Pitcher full of ice water

    • Hot water vessel such as a teapot, coffee pot, etc.

    • Bucket


    Experiment 2 procedure
    Experiment 2: Procedure

    • Approximately 18 inches from one end, bend each tube 90º (see photo on slide 12).

    • Rest the other end on a wooden block (see photo).

    • Vertically support the bent end using the laboratory ring stand (see photo).

    • Attach a funnel to the supported end using the rubber hose and clamp (see photo on slide 13).

    • Make several “toothpick flags” by wrapping a piece of colored tape around a toothpick so that it resembles a small flag (see photo on slide 14).

    • Place the toothpick end of the flag between the metal tube and wooden block (see slide 14 photo).


    Experiment 2 procedure1
    Experiment 2: Procedure

    • Place the hot water vessel onto the hot plate and bring to a boil.

    • Place a bucket beneath the straight end of the copper tube.

    • While the students are looking at the toothpick flag, pour some boiling water into the funnel and observe the amount and direction that the flag spins.

    • Next, pour the ice water into the funnel and observe the flag spinning in the opposite direction.

    • Repeat steps 8 – 10 with the aluminum tube.





    Conclusions
    Conclusions

    ●The more the flag spins, the greater the thermal expansion of the metal tube, thus:

    1. Aluminum has the highest thermal expansion

    2. Copper has the least thermal expansion


    Helpful hints observations
    Helpful Hints & Observations

    • Keep students away from the funnel and bucket when pouring the boiling water!

    • It is helpful to put the tube assembly on a long table.

    • When watching the flag spin, make a note of how many revolutions it spins.


    Experiment 3 heat capacity
    Experiment 3.Heat Capacity

    • Questions

      • What is heat capacity?

    • Answer

      The amount of heat-energy necessary to raise the temperature of 1g of a material 1ºC.


    Experiment 3 materials
    Experiment 3: Materials

    • Hot Plate

    • Beaker or pan that can be used to boil water

    • Metal tongs

    • Rods or cylinders of copper, plastic, and graphite (approx. 1 in. diameter X 1 in. long)

    • Glass beakers (150 ml capacity)

    • Thermometer or thermocouple

    • Stopwatch (or ordinary watch that can measure seconds)


    Procedure1
    Procedure

    1. Weigh three rods, of exactly the same size, made of plastic, graphite, and copper and heat to 100ºC in boiling water.

    2. Using tongs or tweezers drop one of the materials into 100ml of water that is at room temperature.

    3. Measure the temperature increase of the water for 1 minute.

    • The material which most heats the water has the highest heat capacity.

      4. Repeat for the other two materials.


    Conclusions1
    Conclusions

    • The Plastic has the highest heat capacity.

    • The graphite has the 2nd highest heat capacity.

    • The copper has the lowest heat capacity.


    Helpful hints observations1
    Helpful Hints & Observations

    • Thermocouples work best, but if using a thermometer get one that can accurately measure small temperature changes.


    Heat flow in action
    Heat Flow in Action

    Questions

    • How do thermal diffusivity, thermal expansion, and heat capacity work together? -- Thermal conductivity

    • What is thermal conductivity?

      Answers

    • The three heat experiments show how heat flow affects materials.

    • The thermal conductivity is related to all three of the above and is a number that characterizes the speed at which, heat-energy flows through a material of constant area when one end is at a high temperature and the other is at a lower temperature.


    Resources
    Resources

    Materials for most of these experiments can be purchased from hardware stores and scientific equipment suppliers such as Fisher Scientific and Ward’s. Another excellent source is McMaster Carr (www.macmaster.com)


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