Calculate the theoretical flame temperature when ethylene at 25°C is burned with: (a) The theoretical amount of air at 25°C. (b) 25% excess air at 25°C. (c) 50% excess air at 25°C. (d) 100% excess air at 25°C. (e) 50% excess air preheated to 500°C. (f) The theoretical amount of pure oxygen. 4.22. What is the standard heat of combustion of each of the following gases at 25°C if the combustion products

Space-time metric ds2= -dt2+at2dx2+bt2dy2+ct2dz2 (a)how does the area of a rectangle with vertices at ( x=0, y=0, z=0 ), (1,0,0 ), ( 0,1,0 ) and (1,1,0 ) changes with time? (b) if a photon moving in the x direction starts from the origin at t=1, when does it reach x=l? (ds=0 for the trajectory of a photon.) (c) the proper time for a particle is defined by cd=ds. what is the proper time for a particle to move along the trajectory ( x(t)=t, y(t)=0, z(t)=0 ) from t=0 to 1 ? what is the condition on the parameter a so that the velocity of the particle never exceeds the speed of light ?

Anybody wanna ? (picture included? )

What are similarities and differences of reflection, refraction, diffraction and absorption?