# Physics

 Kilocalorie (kcal) the amount of heat needed to raise the temp. of 1 kg of water by 1°C 1 kcal = ___ J 4186 1 cal = ___ J 4.186 Specific Heat: the heat required to raise or lower the temp of 1 kg of a substance by 1°C The amount of heat required to change the temp of a substance by a temp difference... Q=mcΔT Latent heat for a solid-liquid phase change latent heat of fusion (Lf) Latent heat for a liquid-gas phase change Latent heat of vaporization (Lv) Ice → Water Qf > 0 Ice ← Water Qf < 0 Water → Gas Qv > 0 Water ← Gas Qv < 0 What is "A"? Solid C1 What is "B"? Phase Change = Lf Melting What is "C"? Liquid C2 What is "D"? Phase Change = Lv Boiling What is "E"? Gas C3 Where is the boiling point? 140°C Where is the melting point? 110°C Three mechanisms of heat transfer: 1) Conduction2) Convection3) Radiation Define Conduction: heat transfer due to direct contact of objects that have different temps Define Convection: heat transfer due to mass movement of gas or liquid molecules Define Radiation: heat transfered by electromagnetic radiation between objects that have different temperatures Thermal Conductor good conductor of heat Thermal Insulator poor conductor of heat The 1st law of thermodynamics the 1st law is a statement of conservation of energy in terms of thermodynamic variables ΔU, Q &W Q=ΔU+W ΔU = change in the systems internal energy HEAT ENGINE: arrows go ___ and ___ down and out Wnet THERMAL PUMP: arrows go ___ and ___ up and in Win ε = Wnet/Qh The 2nd law of thermodynamics Certain processes do not take place even though they may be consistent with the first law - heat will not flow spontaneously from a cooler body to a warmer body - in a thermal cycle, heat energy cannot be completely transformed into mechanical work. - The work output is always less than the energy input. The Carnot Cycle ε = 1- (Tc/Th) Temp must be in K COPref = Qc/Win Authorandreabyerly ID52458 Card SetPhysics DescriptionPhysics Chapters 11 & 12 Updated2010-12-01T02:16:53Z Show Answers