# Thermal Physics

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• Thermal Physics
• Triple point - all three phases coexist in thermal equilibrium
• Thermal Equilibrium
• Zeroth Law
• Body A & body B are thermal equilibrium with body C, A & B must be thermal equilibrium
• hotter object transfers thermal energy to colder object, both have the same balanced temperature
• One specific temperature and pressure
• SHC
• Energy required per unit mass to change the temperature by 1K or 1°C
• E = mc?Ø
• Energy transferred from heater to  substance - E= IVt
• Specific Latent Heat L=E/m
• Energy require to change phase per unit mass at constant T
• 2. Specific latent heat of vaporisation (LIQUID TO GAS) E=mLv
• Density
• Spacing between the particles affects the density of a substance.
• Solids are generally most dense
• Internal Energy
• T increases the internal energy of a substance, KE will increase, faster moving particles withing substance
• Sum of kinetic and potential energies of atoms or molecules within the substance
• Changing phase
• Solid to liquid
• Internal energy increases, KE and temperature does not change, potential energy increases as bonds are broken
• Once the substance has changed phase, T + KE increase
• Boiling or melting point
• While changing phase, energy transferred to the substance does not change its temperature
• Brownian Motion
• Elastic collisions between water molecules and pollen grains caused the pollen grains to move haphazardly.
• Electrostatic Potential Energy
• Solid
• PE is lowest
• Electrostatic forces is very large negative value
• Liquid
• Electrostatic forces between particles has a negative value
• Negative value means energy is required to break bonds
• Electrostatic forces is very large negative value
• PE is higher
• Gas
• Zero as there is negligible electrical forces between particles
• PE is highest
• Temperature
• Absolute zero
• Internal energy is at its minimum, KE is zero, internal energy not zero as substance still have electrostatic forces between particles
• Measured in kelvins, k
• T(K) = T(°C) + 273
• Absolute scale or thermodynamic scale