Unit 11.Thermal energy transfer

04.30.2020
07:56:51
Dear students, good morning
Today's topic in physics :
Consequences of thermal energy transfer
Pg.no : 157
The important points are
1. Thermal energy transfer from a hotter place. It is the temperature difference that
makes it flow.
2. Conduction is the only way that energy can pass
through a solid. Energy travels through the solid but the solid itself cannot move.
3.Convection is the main way that energy is
transferred in a fluid. Warm fluid moves around, carrying energy with it.
4.Radiation is the only way that thermal energy can travel through empty space. Infrared radiation can also pass through some transparent materials such as air.

*Hot objects have a lot of internal energy. As we have seen above, energy tends to escape from a hot object, spreading to its cooler surroundings by conduction,
convection and radiation. 'This can be a great problem.
* We may use a lot of energy (and money) to heat our homes during cold weather, and the energy simply escapes.
* We eat food to supply the energy we need to
keep our bodies warm, but energy escapes from us at a rate of roughly 100 watts (100 W=100J/s).
To keep energy in something that is hotter than its surroundings, we need to insulate it. Knowing about
conduction, convection and radiation can help us to design effective insulation.
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