### Shot tube

Other Relevant Demos :

• Joule's experiment
Relevant Resource questions :

Concepts demonstrated :

• Conversion of Mechanical Work
• Mechanical equivalent of heat
Diagram of apparatus : Equipment needed :

• Shot tube with lead inside
• Thermocouple
• CCD camera
Method for setting up apparatus :

• Measure the temperature of a known mass of lead shot and place this into a long tube.
• Invert the tube 50 to 100 times and then measure the temperature increase.
Accessories (ie posters etc) :

Physics involved :

Lead shot falling in a tube does mechanical work to produce heat. Measure the temperature of the lead before and after the experiment. Compare the heat to the work done.

How to use the Demonstration :

• Use in lectures when showing the conversion of mechanical energy into heat.
• Discuss this and show how this is the opposite to a heat engine (i.e. heat produces mechanical work).
• Use this as a POE demonstration.
• Start by asking the students what they think will happen to the shot if the tube is inverted 100 times.
• Once the students have worked out that there will be a temperature rise ask them to calculate the work done on the shot (i.e. find mgh x number of inversions) and compare this value to the heat developed.
This is found by multiplying the rise in temperature by mass and specific heat of the shot.
• Measure the temperature of the shot after 100 inversions and compare to the theoreitcal value.
Typical results are theory delta T = 5 deg C, experiment delta T = 3 deg C.
Everyday examples :

• Bend a coat hanger back and forth - thermocouple. Record the temperature (T) versus time. When does it increase temperature most ?
Q Is the heating due to deformation.
A (I think) the heating is due to friction on a microscopic scale.
• A copper (Cu) slug can be hit and the temperature (T) measured. The temperature increase for this experiment is greater than the above experiment (TH 05a).
This is also a good qualitative experiment.
• Belt lead (Pb) with a steel hammer, with a thermocouple on the side or under the lead mass.
Things to do or add :

• Experiment with the thermocouple interface. (Can choice of materials be improved?)
• Compare the above demonstrations in "other (everyday) examples" to the compression of gas e.g. in a syringe.
• See also another experiment - Joule's original experiments. (See Pasco Catalogue for quantitative.)