Thermodynamics

Chapter 7.

Thermodynamics

Heat, radiation, the temperature of space of light, sound, aether, calorific rays, is it a wave or a particle? A current is a consequence of a difference of temperature between two opposite faces.

Friction

The force of static friction between any two surfaces f z≤ µ_s n. Thermal expansion (all dimensions increase) Δr=αr₀ΔT, r= radius, T= temperature the average coefficient of area expansion ΔA=A-A₀=γA₀ΔT, γ=2α the increase in volume ΔV =βV₀ΔT, β=3α average coefficient of volume expansion. Quantity Q of heat is transferred to m kg of a substance, thereby changing its temperature by ΔT st the specific heat c of the substance is defined as C ≡ Q/mΔT heat transferred between a system  of mass m and its surroundings  for a temperature change of ΔT as Q=mcΔT is called phase change the heat required to change the phase of a given mass m of a pure substance is Q=mL L= latent heat, T= temperature, condition H = Q/ΔT = KA(₂-T₁/L) k = thermal conductivity A= area, L=thickness.. Stefan’s law says the rate at which an object emits radiant energy is P=δA _e T⁴ , δ=5.6696 x 10^-8 w/m² x k⁴ and e is a constant called emissivity. All objects radiate and absorb energy in the form of electromagnetic waves hotter than its surrounding, radiates more energy, if it is cooler than its surroundings it absorbs more energy. The 1^st law of thermodynamics is when a system under goes a change from one state to another the change in its internal energy Δu is Δu=u_F –u₁ = Q-w, Q= heat transferred, w=work done + heat enters – heat leaves. Max force is static friction, fsmax between an objet and a surface is proportional to the normal force acting on the object. This max force occurs when the object is on the verge of slipping fs≤u_sn, u_s is the coefficient of static friction. When a body slides over a surface the direction of force of kinetic friction f_k is opposite the direction of the motion and the magnitude is proportional to that of the normal force. The second law of thermodynamics says heat will not flow from cold to a hot object. No heat engine operating in a cycle can absorb thermal energy from a reservoir and just perform an equal amount of work (change in entropy). The heat capacities at constant pressure is 1 atm, near 25 ⁰ c. C (diamond 510 (jk ^-1 kg ^-1 ) specific heat capacity. Entropy is related to the  hardness of the element; hard solids are more ordered and have lower entropies than soft solids. Carbon (diamond) 2.4 jk^-1 hard, Carbon (graphite) 5.7 jk^-1 soft, Density C(diamond) 3.51 (g cm^-3) C(graphite) 2.25 (g cm^-3). Molar volumes C(graphite) 5.33 ¯v(cm³ mol^-1) pressure to C(graphite) → C(diamond) 15.000 atm. Gold has a high charge on the atomic nucleus, the electrons move at speeds approaching that of light, giving gold its color (the theory of relativity). At standard temperature and pressure(70⁰F/20⁰c, 14 psi) an average molecule shimmies at 10 billion times per second. A common place chemical reaction is one million billionth of a second.

Black Body Radiation

Rayleigh-Jeans classical theory of black body radiation predicts that a body will emit more and more radiation the higher the frequencies, this is a contradiction with observations. The “ultra-violet catastrophe” clearly shows that there is an error in the classical approach. The way to avert the ultra-violet catastrophe was discovered by Planck in 1901, by the quantization of the electromagnetic radiation, the photon. The Bose-Einstein distribution law (quantum statistic) for photon and applies to other particles like bosons, alpha-particles, pi mesons etc.

T/K                  P_tot                               λ_max/μm

50                    0.354 w/m²                  57.955

370                  1.063 Kw/m²               7.832

2060                1.021 Mw/m²               1.407

Yoshida et all, 1995. The differential spectrum multiplied by energy cubed.

Every particle of matter in the universe attracts every other particle with a force which diminishes as the square of the distance is increased. The force which holds every respective pair of masses together being the integrated force of their component parts. With gravity there is no selection, no particular atoms, the attraction of gravitation is proportional simply to the quantity of the attracting matter, regardless of its quality. In quantum physics this is reversed.

Gravity is measured by the amount of motion which it can generate in a certain time (earth is 32 feet per second)

Chemical affinity is said to convert heat into light and then again into magnetism and electricity but gravity refuses to be converted, it is a force maintaining itself under all circumstances. By the exertion of a certain pull (gravity) through a certain space, a body is caused to clash with a certain definite velocity, heat is thereby developed, and this is the only sense in which gravity can be said to be converted into heat. In no case is the force which produces the motion annihilates or changes into anything else.