It is not very difficult to accelerate an electron to a speed that is 99.5% of the speed of light, because it has such a very small mass. what is the ratio of the kinetic energy k to the rest energy mc2 in this case? in the definition of what we mean by kinetic energy (k = e - mc2), you must use the full relativistic formula for e, because v/c is not small compared to 1.

Asteel tube (k=50 w/mk) of inner and outer diameter di = 20mm and do=26mm, respectively, is used to transfer heat from hot gases flowing over the tube (h-hot = 200w/m2k) to cold water flowing through the tube (h-cold = 8000 w/m2k). what is the cold-side overall heat transfer coefficient uc? to enhance heat transfer 16 straight fins of rectangular profile are installed longitudinally along the outer surface of the tube. the fins are equally spaced around the circumference of the tube, each having a thickness of 2mm and a length of 15mm. what is the corresponding overall heat transfer coefficient uc? *solve for uc in both cases*