# Physics- Thermal Physics.txt

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1. Define specific heat capacity
• The energy required to change the temperature (of a substance) by 1℃/1K;
• of mass 1kg / per unit mass.
2. 7 Assumptions of an ideal gas
• Point molecules / negligible volume;
• No forces between molecule except for in contact;
• Motion / distribution is random;
• Elastic collisions / no energy lost;
• Obey Newton's laws of motion;
• Collision in zero time;
• Gravity is ignored;
3. Define mole
The molecular weight of the substance in grams / 6.02x10^25 atoms of the substance / same number of particles as in 12g of Carbon-12;
4. Define internal energy
Total energy of component particles / comprises of potential energy + (random) kinetic energy. Measured in Joules (J);
5. Define temperature
• Measure of average kinetic energy of particles;
• indicates direction of (natural) flow of thermal energy;
• measured in Kelvin (K);
6. Describe cooling by evaporation
• Faster / more energetic molecules escape during evaporation;
• slower/ less energetic lower temperature molecules remain;
• so internal energy removed from body;
7. Describe the difference in internal energy of a solid and an ideal gas.
• Internal energy of solid is total KE plus PE of molecules;
• the molecules of an ideal gas comprises of KE only;
8. Explain why the latent heat of vaporization is larger than the latent heat of fusion.
• In boiling, energy is required to break bonds (in vaporization) and to separate molecules;
• in melting (more) energy is available to overcome bond energies of molecules without large separation;
9. Distinguish between evaporation and boiling.
• Evaporation at surface of liquid, boiling occurs throughout liquid;
• evaporation occurs at all temperatures, boiling at boiling point only;
10. Define thermal capacity
Thermal energy required to change temperature by 1K / 1℃;
11. Define thermal equilibrium
Rate of energy absorption is equal to the rate of energy emission / temperature of substance remains constant;
12. Define heating
The (non-mechanical) transfer of energy;
 Author: richardive ID: 217786 Card Set: Physics- Thermal Physics.txt Updated: 2013-05-05 07:51:31 Tags: Physics IB Folders: Description: lsijgowjgd Show Answers: