1.The resistance of a thermistor over a limited range of temperature is given by the equation R= ( where c is a constant and T is the absolute temperature.
What will be the temperature on the Celsius scale of the thermistor at absolute temperature of T = 300K?
2. A woman finds a front windshield of a car covered with ice at -12oC. The ice has a thickness of 4.5 x mm and the windshield area is 125mm2. The density of the ice is 917kg/m3. How much heat is required to melt the ice?
[S.H.C of ice = 2200J/kg/K, Lf =3.3x105J/kg].
3. An electric heater of power 2kW is used to heat 0.8kg of water in a container of heat capacity 300J/K. If the water is initially at 18oC, how long will it take to heat it to the boiling point of 100oC? What mass of water will have boiled away in 4 minutes?
[S.H.C of water = 4200J/kg/K, LV = 2.3X106J/kg]
4. Explain anomalous expansion of water.
5. Steel railway tracks are laid at 8oC. What size of expansion gap are needed 10m long rail sections if the ambient temperature varies from -10oC to 50oC?
[Linear expansivity of steel = 12 x]
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2. Amount of heat required to melt the ice = mc?? +ml
Specific heat capacity of ice, c = 2100J/kg K
specific latent heat of fusion of ice = 336 000J/kg
Volume of ice = 4.7×10^-4×1.25 = 5.875×10^-4
mass of ice = density * volume =5.875×10^-4 × 917 = 0.5387 kg
Amount of heat required = 0.5387 × 2100 × (10.6-0) + 0.5387 × 336000 = 193000J
4. The anomalous expansion of water is an abnormal property of water whereby it expands instead of contracting when the temperature goes from 4o C to 0o C, and it becomes less dense. ... The density becomes less and less as it freezes because molecules of water normally form open crystal structures when in solid form.
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