# force energy entropy free energy. what is force ? f=maf=ma force mass accel

Post on 30-Dec-2015

213 views

Embed Size (px)

TRANSCRIPT

Slide 1

ForceEnergyEntropyFree Energy1What is Force ?F=maforcemassaccel.2What is Force ?S F=maSum of the forces on an object is (directions matter) is equal to the mass of that object multiplied by its acceleration3What is Force ?S F=maSum of the forces on an object is (directions matter) is equal to the mass of that object multiplied by its acceleration4Gravitational Fg=mg

mThis is a special case. When one of the two objects is Earth5Gravitation m1Fg=Gm1m2r2m2rG = 6.671011N m2 kg26Electrostatic q1Fe=keq1q2r2q2rke=9.0 x 109 Nm2/C2q is the amount of charge on each objectCharge of an electrone = 1.6 * 10-19 C

C= Coulomb a unit of charge7ElectrostaticsCoulombs LawF = ke q1q2/r2ke=9.0 x 109 Nm2/C2e = 1.6 x 10-19C

Gravity

Newtons Law of Gravitation

F =Gm1m2/r2

G = 6.6731011N m2 kg2.

8

9SarahAshleyChristianZack P. CharlieJeremyDominiqueCarlyTrevorKarstenJessyZack J. SamAhmetJohnCoreyAakashHunterCarsonShaneNickMax123456Nanocalc Teams10What is Energy?Capacity to do Work. What does this mean?EnergyStored (Potential) Chemical NuclearMagneticElectrostaticMass

EM Radiation Light X-raysmicrowavesMotion (Kinetic) 11Energetics of an ExplosionTNTIn what form is the energy?12Energetics of an ExplosionBang!In what form is the energy?13Potential Energy U (or E)

14Potential Energy U (or E)

F15Force, Energyand Bonding16Force, Energyand BondingAB17ShakyNano Property #2:All things shake, wiggle, shiver and move all around at the nanoscale.

18Brownian Motion

In both cases the fluorescent particles are 2 microns in diameter. The left picture shows particles moving in pure water; the right picture shows particles moving in a concentrated solution of DNA, a viscoelastic solution in other words. The movies are 4 seconds of data, total; you can see a slight jump in the movie when it loops around. http://www.deas.harvard.edu/projects/weitzlab/research/brownian.html19Basic ThermodynamicsZeroth Law: If two systems are in thermal equilibrium with a third system, they are in thermal equilibrium with each other. First Law: Energy in the universe is conserved (it is also conserved in a closed system).Second Law : Entropy increases20What is Entropy ?21What is entropy ?A count of the number of equivalent states of a systemEquivalent ?States ??22What is Temperature anyway? What is it a measure of ?

MOTIONIn specific Scientific Terms: Temperature is a measure of the average kinetic energy of the particles in a system. TEMPERATURE23Heat is nano-scopic motionVery, Very coldWarmHot24Flow of Heat25Thermal EnergyEthermal=1/2 k * Temperaturek = Botzmanns constant (1.38*10-23J/K)Ethermal=1/2 kTAverage Energy of each degree of freedom in a system. At room Temperature, Ethermal= 4*10-21 J or 0.025 eV26Fahrenheit, Celsius, KelvinKelvin3000100-200-100-27320027337317373047357357232212-328-148-459392CelsiusFahrenheit27Kinetic EnergyEkinetic=1/2 (mass)*(velocity)2Ekinetic= 1/2 mv2We can set the thermal energy of an object equal to its kinetic energy to see how fast it is moving. This is appropriate for relatively free particles.Ekinetic=Ethermal1/2 mv2 = 1/2 kTv=(kT/m)1/228Thermally induced Kinetic Energyv=(kT/m)1/2 (appropriate for a free particle)Person 100kg6*10-12m/sGrain of Sand10 mg7*10-8m/s (10nm/s)10 micron bead 4*10-12kg 20 microns/s1 micron bead4*10-15kg 700 micron/sVirus5*10-19kg9 cm/sOxygen Molec.5*10-26kg270 m/s29Thermal Vibrations:Carbon Nanotube

30Entropy31EntropyDS < 032Entropy33EntropyDS < 034Entropy35EntropyDS > 036Bonding/AssemblyBond Energy vs. Thermal Energy37Force, Energyand Bonding38Free EnergyEnthalpy and Entropy39Potential EnergyxEb=bond energyxTransition StateUb0Uactiv.40xBonding / Assembling41xDisassociating42Potential EnergyxUbx0Bonding / Assembling43Potential EnergyxUbx0Disassociating44Effects of thermal energy on Bond StrengthPotential EnergyxUbkBTThermal Energy affects the Dissociation Constant and Bond Strength. Thermal Energy aids the dissociation of a bond. 045Bond Strength: Boltzman FactorWhat is the probability that a bond will spontaneously dissociate????P=e-Ub/kTkT at room temperature = 0.025 meVThe rate of dissociation rd = w e-Ub/kBTAttempt frequencyVibrational frequency of bond orinverse relaxation timeProbability per attemptRate of dissociation46Force, Energyand Bonding47Force, Energyand BondingABDU = UB UA < 0Spontaneous & Stable48Gibbs Free EnergyG = H - TSThermodynamic PotentialHelmholtz Free EnergyF = U - TSTempEntropyEnthalpyU + PVPotential Energy (chemical typically)49Thermodynamic PotentialHelmholtz Free EnergyF = U - TSDF = DU - TDSWhen change in free energy is negative, process is spontaneousDefine System50DF = DU TDS

DU = ? > or < 0 ?DS = ? > or < 0 ?When change in free energy is negative, process is spontaneous51Bond Strength: Boltzman FactorWhat is the probability that a bond will spontaneously dissociate????P=e-Ub/kTkT at room temperature = 0.025 meVThe rate of dissociation rd = w e-Ub/kBTAttempt frequencyVibrational frequency of bond orinverse relaxation timeProbability per attemptRate of dissociation52DU > or < 0 ?DS > or < 0 ?DF = DU - TDS53DU > or < 0 ?DS > or < 0 ?DF = DU - TDS54ABCDEWhich representative state of the fiber has highest entropy?5556

Recommended