Solids also expand, with heating, but less so, than gases. They expand in three dimensions.
Heat: Expansion of solids.
Solids, when heated, also expand. But by a much smaller amount.
Steel bridge p.112 Expansion joint
Jar lids that are too tight: heat 'em.
Glass cracking when going from hot to cold.
A copper pipe 2 meters long and is at room temperature ( 28 degrees celsius). Water at the boiling point (100 degrees celsius) is sent through the pipe. By how much does it increase in lenght?
A steel rebar rod is 10 m long in Sapporo, Japan, in winter at -20 degrees celsius. Six months later the rebar is in summer weather at 30 degrees celsius. What is the increase in lenght of the rebar?
Specific Heat :
The amount of heat energy an object can hold.
Heat contained = mass * specific heat capacity * change in temperature
Q = m * c * change in temperature
- more mass, more heat held
-the grater the heating( temp. change), the greater the temp. drop, the greater the heat lost.
Water : 1 calorie to raise 1 gram , 1 degree celsius.
Aluminum : 0.22 calorie to raise 1 gram , 1 degree celsius.
Suppose 50 g of Cu at 100 degrees celsius is added to 100g of water at 28 degrees celsius. What is the final temperature of the water ?
The copper loses heat to the water falling from 100 degrees celsius to its final temperature. The water gains heat from the copper, rising from 28 degrees celsius to its final temperature. As the copper is in the water, the final temperature must be the same for the water and copper.
The other way around : 50g of an unknown substance at 100 degrees celsius is added to 100g of water at 28 degrees celsius. The final temp. is 35 degrees. What was the specific heat capacity of the unknown substance.
heat gained (by water) = heat lost by unknown
The First Law of Thermodynamic : Energy is conserved. Energy lost by one system must be gained by same other system.
The Second Law of Thermodynamic : Each time the energy is transformed, same energy is converted to heat. This heat is usually not then useful for further work.
If the amount of disorder in a system is called the entropy of the system, then all systems tend toward more disorders. ( greater entropy)
How does heat moves,
Limiting heat loss or blocking heat.
convertion - pot lids so inside inside heats faster. Energy transformed by the physical motion upwards of a parcel of hot air.
radiation - almost anything with any thickness.Energy (not necessarily just heat) in the form of electromagnetic waves.
conduction - use thing that conducted heat less well. Try sticking something metal in a fire and then sticking in a stick. Energy is transmitted by the colliding of molecules in a substance. Some metarials conduct heat better than others, eg. metal.
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