in white light coloured objects reflect some of the light while the rest is absorbed. Black objects absorb all colours. If you have a red coat on it, appears red because only red light is reflected. Which colours are absorbed by the red coat.

Which two particles are found in the center of an atom

This is the number of complete movements of a wave per second.

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*