Extra Explaining Questions - THERMAL EXPANSION

THERMAL EXPANSION

1. A compound strip of brass and iron is straight as room temperature. Draw a labeled diagram to show its appearence when it has been;
   


2. A student designs anexperiment to calculate the specific latent heat of fusion of ice. He uses a heater to melt ice as shown in figure below.
   
   Explain why the ice should be allowed to reach 0 °C rather than being taken straight out of the freezer at a temperature of -18 °C
   [Show answer]

   If ice will be first allowed to reach 0 °C, all energy supplied by heater will be used to melt the ice to water (H=mL_f). But when the ice will be transfered straight out from the freezer at a temperature of -18 °C some of heat supplied by heater will lost by raising ice from -18 °C to 0 °C before melting


3. a) When a gas is rapidly compressed by a piston, the temperature of the gas rises.
   [Show answer]

   When the gas is compressed the pressure increases due to decrease of volume, as described by Boyle's law. The increase of pressure of a gas rises its absolute temperature as explained by the Pressure law.
   
   b) When a gas expands rapidly the temperature of the gas falls. Give a reason why.
   [Show answer]

   When the gas is expands the pressure decreases due to increase of volume, as described by Boyle's law. The decrease of pressure of a gas lowers its absolute temperature as explained by the Pressure law.


4. A compound strip of brass and iron is straight as room temperature. Draw a labeled diagram to show its appearence when it has been;
   1. heated to a high temperature
   2. cooled below 0 °C


5. With the aid of a graph, explain the effect of temperature on the density of water.


6. Anomalous expansion of water is said to have both useful and unuseful. Using the knowledge of anomalous expansion of water justify the statement above using one point in each case