2/26/2014 Experiment: Thermal Expansion & Latent Heat of Vaporization & Pressure vs Volume and Pressure vs Temperature

Thermal Expansion

1) After the ring been heated, area of the hole expanded.  

2) Different material has different thermal expansion.  

Using steam generator to heat up the metal pipe and using experiment data to determine material of the metal pipe.  

Graphs of temperature vs time and angle vs time.  

  Determine the relationship between angular displacement of pulley and linear displacement; then plug it into the equation of alpha to calculate thermal expansion rate.  

Proving the equation of alpha with uncertainty of measured diameter and recalculate the thermal expansion rate.  

Physical meaning of thermal expansion:  
When a object is heated, its particles begin moving more and thus usually maintain a greater average separation.

Latent Heat of Vaporization

Ideal graph of temperature vs time.  

Using immersion heater to heat up 200 ml of water till it boiled.  

Graph of temperature vs time.  

Recorded experiment data and calculating the latent heat of vaporization.  

Calculating standard deviation of latent heat base on each group's experimental data.  

Pressure vs Volume and Pressure vs Temperature

Graph: Pressure vs Volume

Equations: Relationship between weight and area

Experimental graph of pressure vs volume by using pressure detector to measure pressure changed over volume.  

Graph of pressure vs temperature.  

Physical meaning of pressure vs temperature:  

When the speed of a gas's molecules increase, the gas molecules hit their container more often.  The more frequently the gas impacts the container walls, the higher the pressure.  So, as temperature increase, the pressure also increases.  If the gas cools, the impacts are less frequent and the pressure decrease.  

Conclusion:  
In thermal expansion, temperature increase, the volume of object also increases.  In latent heat of vaporization, the latent heat we measured(1400000J/kg) is way off then the actual data(2256000J/kg).  The possible error in our experiment is the way we measure the volume of water.  We should use scale instead graduated cylinder to measure the mass of water.  Because scale is more accurate than graduated cylinder.  In pressure vs volume/temperature, pressure and volume has inverse proportion relationship.  On the other, pressure is directly proportional to temperature.