THERMAL EXPANSION
1.
A student designs an
experiment to calculate the specific latent heat of fusion of ice. He uses a heater
to melt ice as shown in figure below.
[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=mLf). 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
2.
a) When a gas is rapidly compressed by a piston, the
temperature of the gas rises. Give a reason why.
[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.
3.
A compound strip of brass and iron is straight as room temperature. Draw a labeled diagram to show its appearence when it has been;
i) heated to a high temperature
ii) cooled below 0 °C
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