AQA A Level Physics 6.2 Thermal Physics

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OF THERMODYNAMICS Q=AU + W Q = heat energy to the AU= change of internal W = work done thermometer by the Measuring Specific Latent Heat Vaporisation system - energy system BALANCE to measure electric submersion heater P= IxV Q= Pxt start tim when T= 100°C or other mass evaporated boiliy point Work done Work Fd Pressure = = = F = PA Sanity Check! Density of Water = 1000 kgm²³ Density of Air = 1 kgmn-3 very Molecules in constant random motion Molecules fill their container Fusion pV PV = nRT (obviously) Balance P=IxV Q = Pxt Ice! · Water! IDEAL GAS Assumptions: - Molecules FAR apart (no intermolecular forus unless they collide) Molecules au -Force за W=PAd W=PAV constant pressure only! mass melted To measure A.d = AV Jonathan small compared to the size of the container Y > Control Balame (No mater) Pressure Particles collide with container walls in momentum Experience change L Fore on particle (N2L) Force on wall (N3L) F Pressure = pressure on wall IDEAL GAS LAW (alpha version, not feature-complete) Boyle's law: Pressure law: pat when T-OK, рай PV = constant (constant temp. & amount of p=0 kelvin! What is the MOLE? This 0000 000 Ci dozen eggs Charles' law: V&T or == constant guy! ← = constant (constant volume & amount of gas) or - Ek = 1/2mv² => Ek↑, or (constant pressure & amount of gas) - Particle mass = mass ↑ KINETIC THEORY OF GASES -What affects pressure? - # of Particles #1 L Velocity ↑ of gas) I have 6.022 x 1023 children!! mole of molecules. No, I said yo child is a mde. collision rate 1 > greater momentum, ar collision rate 1 KINETIC GAS EQUATION PV=NCANS ↳ Ap↑ A₁, force 4p ↑ RMS high WATER BATH Pressure & temp. sensors. Manometer on walls ↑ A 1, force pressurel Data or Togger CRMs Can be written as <c²> (² P: Pressure [Pa] V: Volume [m³] N: # of molecules M: Mass of 1 molecule [kg] CRMS: RMS molecular speed [ms] RMS: root mean square Vi on walls ↑ Computer) pressure ерди rate of change of momentum (1)₁, At force on walls ↑ CRMS is the mean square speed. MORE ON THE KINETIC GAS EQUATION CRMS= 100 200 300² + 400² 4 •square root The proof is out of |-- X + back & forth! Notice: 4 enbe volume, side length MN syllabus. l ← # of particles u= Pressure on wall = m Nu² /l lxl (but still How often does this happen? total mass V = t initial distance travelled = 21 = P³ good to know) particle moves in tve x dir. = mu Sum of 4- 24 m Nu² :1 = density square ⇓ Арг-2 ми (V= volume) randomly, p=qu² = }pc²={_.mw.c ⇒pV= / Nm c² CRMS will be the mean of the square velocities wall times per second? [Force of all particles = mus + mu² my ² +...+ # (u²+ us² + us +..) = Nu muż Mu M e ² = U²+U²+U²} +... N (and • velocities of each particle ²= V² =W² proving how many fat = t = 44₁ Considering 3 AXES : resultant C³² = U²³ + √² + W² (since u²+ uỷ + U3³.…... V₁² + V² + V³ +...+ N N Assuming particles move after rebound (elastic collision) p=-mu it) p=pu² (pressure Force= ・Af = 4px Prequency At = -2mu. substitute ㅎㅎ velocity, c⇒ c ² = u²+ √² + w² (pythagoras' theorem) Fore of one Z1 = - m² l particle. on wall in ONE AXIS) C² = 3ū² (just stastically) W² + W₂² + W ².... _ Ci+c²₂+ C ³ + ...) N N mu² ㅅ Imole IDEAL GAS EQN PV = nRT = Nmc² gas, PV =3 Nmc² č= 3pV Nm RT=mc²=mc². NA Mc²= R.T NA 3 R 1/2 m² = 2²/12 · Ñ₁² . = mc²=//kT 1. T X KINETIC GAS EQN =NA = Avogadro's number, 6.02 x 1025 •Ek 3 x 100000 x 0.024 6.02x1023 x 4.8x10-26 k=RA² = Boltzann's Constant NA Ek = 1/2 mc ² = Average kinetic a T Ek = 1/2kT 100 kPa, 0.024m³, 4.8x10726 kg per energy Temp. proportional to average molecule 499.1687... 500ms" of one particle kinetic energy!